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WEATHER WEATHER AND CLIMATE AND CLIMATE Britannica Illustrated Science Library Britannica Illustrated Science Library Encyclopædia Britannica, Inc. Chicago ■ London ■ New Delhi ■ Paris ■ Seoul ■ Sydney ■ Taipei ■ Tokyo PDF电子书基地 http://dayo1982.400gb.com
Britannica Illustrated Britannica Illustrated Science Library Science Library © 2008 Editorial Sol 90 All rights reserved. Idea and Concept of This Work: Editorial Sol 90 Project Management: Fabián Cassan Photo Credits: Corbis, ESA, Getty Images, Graphic News, NASA, National Geographic, Science Photo Library Illustrators: Guido Arroyo, Pablo Aschei, Gustavo J. Caironi, Hernán Cañellas, Leonardo César, José Luis Corsetti, Vanina Farías, Joana Garrido, Celina Hilbert, Isidro López, Diego Martín, Jorge Martínez, Marco Menco, Ala de Mosca, Diego Mourelos, Eduardo Pérez, Javier Pérez, Ariel Piroyansky, Ariel Roldán, Marcel Socías, Néstor Taylor, Trebol Animation, Juan Venegas, Coralia Vignau, 3DN, 3DOM studio, Jorge Ivanovich, Fernando Ramallo, Constanza Vicco Composition and Pre-press Services: Editorial Sol 90 Translation Services and Index: Publication Services, Inc. Portions © 2008 Encyclopædia Britannica, Inc. Encyclopædia Britannica, Britannica, and the thistle logo are registered trademarks of Encyclopædia Britannica, Inc. Britannica Illustrated Science Library Staff Encyclopædia Britannica, Inc. Editorial Jacob E. Safra, Chairman of the Board Michael Levy, Executive Editor, Core Editorial John Rafferty, Associate Editor, Earth Sciences Jorge Aguilar-Cauz, President William L. Hosch, Associate Editor, Mathematics and Computers Michael Ross, Senior Vice President, Corporate Development Kara Rogers, Associate Editor, Life Sciences Rob Curley, Senior Editor, Science and Technology Dale H. Hoiberg, Senior Vice President and Editor David Hayes, Special Projects Editor Marsha Mackenzie, Director of Production Art and Composition Steven N. Kapusta, Director Carol A. Gaines, Composition Supervisor Christine McCabe, Senior Illustrator International Standard Book Number (set): 978-1-59339-797-5 Media Acquisition International Standard Book Number (volume): Kathy Nakamura, Manager 978-1-59339-801-9 Britannica Illustrated Science Library: Copy Department Weather and Climate 2008 Sylvia Wallace, Director Julian Ronning, Supervisor Printed in China Information Management and Retrieval Sheila Vasich, Information Architect Production Control Marilyn L. Barton Manufacturing Kim Gerber, Director www.britannica.com PDF电子书基地 http://dayo1982.400gb.com
Weather and Climate PDF电子书基地 http://dayo1982.400gb.com
Contents PHOTOGRAPH ON PAGE 1 Tornado during an electrical storm, in Oklahoma, 1973 Climatology Page 6 Surface Factors Page 18 Meteorological Phenomena Page 36 Meteorology Page 62 Climate Change Page 74 PDF电子书基地 http://dayo1982.400gb.com
Contents PHOTOGRAPH ON PAGE 1 Tornado during an electrical storm, in Oklahoma, 1973 Climatology Page 6 Surface Factors Page 18 Meteorological Phenomena Page 36 Meteorology Page 62 Climate Change Page 74 PDF电子书基地 http://dayo1982.400gb.com
A Sum “ he flutter of a butterfly's wings in different: when there should have been sunshine, there is rain; people who planned to go to the Brazil can unleash a tornado in T Florida.” That was the conclusion beach find they have to shut themselves up in the of Factors arrived at in 1972 by Edward Lorenz after basement until the hurricane passes. All this dedicating himself to the study of uncertainty causes many people who live in areas meteorology and trying to find a way of that are besieged by hurricanes or tropical predicting meteorological phenomena that storms to live in fear of what might happen, might put the lives of people at because they feel very vulnerable to changes in STRONG WINDS AND risk. In effect, the atmosphere weather. It is also true that natural phenomena, TORRENTIAL RAINS Between September 20 and is a system so complicated such as tornadoes, hurricanes, and cyclones, do September 25, 1998, that many scientists define not in themselves cause catastrophes. For Hurricane Georges lashed the Caribbean, leaving thousands it as chaotic. Any forecast example, a hurricane becomes a disaster and of people homeless. can rapidly deteriorate causes considerable damage, deaths, and because of the wind, the economic losses only because it strikes a appearance of a warm populated area or travels over farmland. Yet in front, or an unexpected society, the idea persists that natural phenomena storm. Thus, the equate to death and destruction. In fact, difference continues experience shows that we have to learn to live to grow with these phenomena and plan ahead for what geometrically, and might happen when they occur. In this book, the reality of the along with spectacular images, you will find next day is not the useful information about the factors that one that was determine weather and climate, and you will be expected but able to understand why long-term forecasts are entirely so complicated. What changes are expected if global warming continues to increase? Could the polar ice caps melt and raise sea levels? Could agricultural regions slowly become deserts? All this and much more are found in the pages of the book. We intend to arouse your curiosity about weather and climate, forces that affect everyone. PDF电子书基地 http://dayo1982.400gb.com
A Sum “ he flutter of a butterfly's wings in different: when there should have been sunshine, there is rain; people who planned to go to the Brazil can unleash a tornado in T Florida.” That was the conclusion beach find they have to shut themselves up in the of Factors arrived at in 1972 by Edward Lorenz after basement until the hurricane passes. All this dedicating himself to the study of uncertainty causes many people who live in areas meteorology and trying to find a way of that are besieged by hurricanes or tropical predicting meteorological phenomena that storms to live in fear of what might happen, might put the lives of people at because they feel very vulnerable to changes in STRONG WINDS AND risk. In effect, the atmosphere weather. It is also true that natural phenomena, TORRENTIAL RAINS Between September 20 and is a system so complicated such as tornadoes, hurricanes, and cyclones, do September 25, 1998, that many scientists define not in themselves cause catastrophes. For Hurricane Georges lashed the Caribbean, leaving thousands it as chaotic. Any forecast example, a hurricane becomes a disaster and of people homeless. can rapidly deteriorate causes considerable damage, deaths, and because of the wind, the economic losses only because it strikes a appearance of a warm populated area or travels over farmland. Yet in front, or an unexpected society, the idea persists that natural phenomena storm. Thus, the equate to death and destruction. In fact, difference continues experience shows that we have to learn to live to grow with these phenomena and plan ahead for what geometrically, and might happen when they occur. In this book, the reality of the along with spectacular images, you will find next day is not the useful information about the factors that one that was determine weather and climate, and you will be expected but able to understand why long-term forecasts are entirely so complicated. What changes are expected if global warming continues to increase? Could the polar ice caps melt and raise sea levels? Could agricultural regions slowly become deserts? All this and much more are found in the pages of the book. We intend to arouse your curiosity about weather and climate, forces that affect everyone. PDF电子书基地 http://dayo1982.400gb.com
Climatology SATELLITE IMAGE GLOBAL EQUILIBRIUM 8-9 In this image of the Earth, PURE AIR 10-11 one clearly sees the movement of water and air, which causes, ATMOSPHERIC DYNAMICS 12-13 among other things, COLLISION 14-15 temperature variations. COLORS IN THE SKY 16-17 he constantly moving environment. All these constitute what is Within this complex system, one of the moisture into the atmosphere. Water, atmosphere, the oceans, the called the climatic system; they fundamental variables is temperature, with all its processes (evaporation, continents, and the great permanently interact with one another which experiences the most change and condensation, convection), also plays a masses of ice are the principal and transport water (as liquid or vapor), is the most noticeable. The wind is fundamental role in Earth's climatic T components of the electromagnetic radiation, and heat. important because it carries heat and system. PDF电子书基地 http://dayo1982.400gb.com
Climatology SATELLITE IMAGE GLOBAL EQUILIBRIUM 8-9 In this image of the Earth, PURE AIR 10-11 one clearly sees the movement of water and air, which causes, ATMOSPHERIC DYNAMICS 12-13 among other things, COLLISION 14-15 temperature variations. COLORS IN THE SKY 16-17 he constantly moving environment. All these constitute what is Within this complex system, one of the moisture into the atmosphere. Water, atmosphere, the oceans, the called the climatic system; they fundamental variables is temperature, with all its processes (evaporation, continents, and the great permanently interact with one another which experiences the most change and condensation, convection), also plays a masses of ice are the principal and transport water (as liquid or vapor), is the most noticeable. The wind is fundamental role in Earth's climatic T components of the electromagnetic radiation, and heat. important because it carries heat and system. PDF电子书基地 http://dayo1982.400gb.com
8 CLIMATOLOGY WEATHER AND CLIMATE 9 Global Equilibrium SOLAR RADIATION Sun Cryosphere About 50 percent of the solar Represents regions of the Earth energy reaches the surface of the Essential for climatic activity. covered by ice. Permafrost exists The subsystems absorb, Earth, and some of this energy is exchange, and reflect energy where the temperature of the soil he Sun's radiation delivers a large amount of energy, transferred directly to different that reaches the Earth's surface. or rocks is below zero. These which propels the Earth's extraordinary mechanism called layers of the atmosphere. Much of For example, the biosphere regions reflect almost all the light T the climatic system. The components of this complex the available solar radiation leaves incorporates solar energy via they receive and play a role in the the air and circulates within the circulation of the ocean, regulating photosynthesis and intensifies system are the atmosphere, hydrosphere, lithosphere, other subsystems. Some of this the activity of the hydrosphere. its temperature and salinity. cryosphere, and biosphere. All these components are constantly energy escapes to outer space. ALBEDO OF RECENTLY interacting with one another via an interchange of materials and 80% FALLEN SNOW energy. Weather and climatic phenomena of the past—as well ALBEDO as of the present and the future—are the combined expression WINDS The percentage of solar 50% The atmosphere is always in of Earth's climatic system. motion. Heat displaces masses radiation reflected by the THE ALBEDO OF SUN of air, and this leads to the climatic subsystems. LIGHT CLOUDS Lithosphere general circulation of the This is the uppermost solid layer of atmosphere. the Earth's surface. Its continual formation and destruction change the Atmosphere Biosphere surface of the Earth and can have a large impact on weather and climate. Part of the energy received Living beings (such as plants) For example, a mountain range can from the Sun is captured by the influence weather and climate. They PRECIPITATION act as a geographic barrier Water condensing in the atmosphere. The other part is form the foundations of ecosystems, atmosphere forms droplets, and to wind and moisture. absorbed by the Earth or which use minerals, water, and other gravitational action causes them reflected in the form of heat. chemical compounds. They contribute to fall on different parts of the Greenhouse gases heat up the materials to other subsystems. atmosphere by slowing the Earth's surface. release of heat to space. about 10% EVAPORATION HEAT The surfaces of water ALBEDO OF THE TROPICAL FORESTS bodies maintain the HEAT quantity of water vapor in the atmosphere within normal limits. SMOKE Particles that escape into the atmosphere can retain their heat Night and day, coastal breezes exchange energy and act as between the hydrosphere HUMAN condensation nuclei and the lithosphere. ACTIVITY for precipitation. RETURN TO THE SEA UNDERGROUND CIRCULATION The circulation of water is produced by gravity. Water from the hydrosphere infiltrates the lithosphere and circulates therein until it reaches the large water ASHES reservoirs of lakes, rivers, Volcanic eruptions bring nutrients to and oceans. the climatic system where the ashes fertilize the soil. Eruptions also block the rays of the Sun and thus reduce the MARINE CURRENTS amount of solar radiation received by the Earth's surface. This causes cooling of the atmosphere. Hydrosphere SOLAR The hydrosphere is the name for all ENERGY water in liquid form that is part of the GREENHOUSE EFFECT climatic system. Most of the lithosphere 3% Some gases in the atmosphere are very is covered by liquid water, and some of ALBEDO OF THE OZONE ATMOSPHERE effective at retaining heat. The layer of the water even circulates through it. BODIES OF WATER LAYER air near the Earth's surface acts as a shield that establishes a range of temperatures on it, within which life can exist. PDF电子书基地 http://dayo1982.400gb.com
8 CLIMATOLOGY WEATHER AND CLIMATE 9 Global Equilibrium SOLAR RADIATION Sun Cryosphere About 50 percent of the solar Represents regions of the Earth energy reaches the surface of the Essential for climatic activity. covered by ice. Permafrost exists The subsystems absorb, Earth, and some of this energy is exchange, and reflect energy where the temperature of the soil he Sun's radiation delivers a large amount of energy, transferred directly to different that reaches the Earth's surface. or rocks is below zero. These which propels the Earth's extraordinary mechanism called layers of the atmosphere. Much of For example, the biosphere regions reflect almost all the light T the climatic system. The components of this complex the available solar radiation leaves incorporates solar energy via they receive and play a role in the the air and circulates within the circulation of the ocean, regulating photosynthesis and intensifies system are the atmosphere, hydrosphere, lithosphere, other subsystems. Some of this the activity of the hydrosphere. its temperature and salinity. cryosphere, and biosphere. All these components are constantly energy escapes to outer space. ALBEDO OF RECENTLY interacting with one another via an interchange of materials and 80% FALLEN SNOW energy. Weather and climatic phenomena of the past—as well ALBEDO as of the present and the future—are the combined expression WINDS The percentage of solar 50% The atmosphere is always in of Earth's climatic system. motion. Heat displaces masses radiation reflected by the THE ALBEDO OF SUN of air, and this leads to the climatic subsystems. LIGHT CLOUDS Lithosphere general circulation of the This is the uppermost solid layer of atmosphere. the Earth's surface. Its continual formation and destruction change the Atmosphere Biosphere surface of the Earth and can have a large impact on weather and climate. Part of the energy received Living beings (such as plants) For example, a mountain range can from the Sun is captured by the influence weather and climate. They PRECIPITATION act as a geographic barrier Water condensing in the atmosphere. The other part is form the foundations of ecosystems, atmosphere forms droplets, and to wind and moisture. absorbed by the Earth or which use minerals, water, and other gravitational action causes them reflected in the form of heat. chemical compounds. They contribute to fall on different parts of the Greenhouse gases heat up the materials to other subsystems. atmosphere by slowing the Earth's surface. release of heat to space. about 10% EVAPORATION HEAT The surfaces of water ALBEDO OF THE TROPICAL FORESTS bodies maintain the HEAT quantity of water vapor in the atmosphere within normal limits. SMOKE Particles that escape into the atmosphere can retain their heat Night and day, coastal breezes exchange energy and act as between the hydrosphere HUMAN condensation nuclei and the lithosphere. ACTIVITY for precipitation. RETURN TO THE SEA UNDERGROUND CIRCULATION The circulation of water is produced by gravity. Water from the hydrosphere infiltrates the lithosphere and circulates therein until it reaches the large water ASHES reservoirs of lakes, rivers, Volcanic eruptions bring nutrients to and oceans. the climatic system where the ashes fertilize the soil. Eruptions also block the rays of the Sun and thus reduce the MARINE CURRENTS amount of solar radiation received by the Earth's surface. This causes cooling of the atmosphere. Hydrosphere SOLAR The hydrosphere is the name for all ENERGY water in liquid form that is part of the GREENHOUSE EFFECT climatic system. Most of the lithosphere 3% Some gases in the atmosphere are very is covered by liquid water, and some of ALBEDO OF THE OZONE ATMOSPHERE effective at retaining heat. The layer of the water even circulates through it. BODIES OF WATER LAYER air near the Earth's surface acts as a shield that establishes a range of temperatures on it, within which life can exist. PDF电子书基地 http://dayo1982.400gb.com
11 Cirrus WEATHER AND CLIMATE Other gases 0.03% DISTANT ORBITS Polar meteorological satellites orbit in the Military satellites Air friction shortens their useful life. become superheated by friction with the molecules of the gas in the atmosphere. Particles that skip across the atmosphere are called shooting stars. Weather balloons are used to make weather forecasts. They record the conditions of the The Ozone Layer stops most of the Sun's ultraviolet rays. GASES IN THE AIR Carbon dioxide 0.04% Argon 0.93% exosphere. Meteors Forecasts stratosphere. 59° F (15° C) AVERAGE TEMPERATURE OF THE EARTH'S SURFACE Cosmic rays Come from the Sun and other radiation sources in outer space. When they collide with the molecules of gas in the atmosphere, they produce a rain of particles. High mountains Any mountains higher than 5 miles (8 km) above sea level. The decrease of oxygen with altitude makes it difficult to breathe above 2.5 miles (4 km). Nitrogen Oxygen 78% 21% GREENHOUSE EFFECT Produced by the absorption of infrared emissions by the greenhouse gases in the atmosphere. This natural phenomenon helps to keep the Earth's surface temperature stable. 6% of solar radiation is reflected by the atmosphere. 19% of solar radiation is absorbed by the gases in the atmosphere. 20% of solar radiation is reflected by the clouds. SOLAR RADIATION Safe flights The absence of meteorological changes in this region makes it safer for commercial flights. 4% A small amount of solar radiation is reflected by the oceans and the ground. PDF电子书基地 http://dayo1982.400gb.com and type of solar energy that reaches the surface of composition allows it to regulate the quantity the Earth. The atmosphere, in turn, absorbs energy oxygen, carbon dioxide, ozone, and water vapor. component, it also contains other gases, such as influence on the Earth's weather and climate. microscopic particles in the air, have a great Created in the upper layers Auroras of the atmosphere when the solar wind generates electrically charged particles Noctilucent clouds The only clouds that exist above the troposphere. They are the objects of intense study. Tropical storm clouds 51% of solar radiation is absorbed by the Earth's surface. Pure Air he atmosphere is the mass of air that envelops the surface of the Earth. Its radiated by the crust of the Earth, the polar ice caps and the oceans, and other surfaces on the planet. Although nitrogen is its principal These less abundant gases, along with EXOSPHERE This layer, which begins at an altitude of about 310 miles (500 km), is the upper limit of the atmosphere. Here material in plasma form escapes from the Earth, because the magnetic forces acting on them are greater than those of gravity. and the N 2 Rocket probes Used for scientific studies of the higher regions of the atmosphere MESOSPHERE Located between an altitude of 30 to 55 miles (50-90 km), it absorbs very little energy yet emits a large amount of it. This absorption deficit causes the temperatures to decrease from 60° F to -130° F (20° C to -90° C) in the upper boundary of the mesopause. CLIMATOLOGY T THERMOSPHERE Found between an altitude of 55 and 300 miles (90- 500 km). The O 2 absorb ultraviolet rays and reach temperatures greater than 1,800° F (1,000° C). These temperatures keep the density of gases in this layer very low. STRATOSPHERE Extends from an altitude of 6 miles to 30 miles (10-50 km). The band from 12 to 19 miles (20-30 km) has a high concentration of ozone, which absorbs ultraviolet radiation. A thermal inversion is produced in this layer that is expressed as an abrupt temperature increase beginning at an altitude of 12 miles (20 km). TROPOSPHERE Starts at sea level and goes to an altitude of six miles (10 km). It provides conditions suitable for life to exist. It contains 75 percent of the gases in the atmosphere. Meteorological conditions, such as the formation of clouds and precipitation, depend on its dynamics. It is also the layer that contains pollution generated by human activities. 10
12 CLIMATOLOGY WEATHER AND CLIMATE 13 Atmospheric Dynamics + POLAR CELL JET STREAM 10 miles STRATOSPHERE At the poles, cold air descends Velocity 55 to 250 miles per and moves toward the Equator. -- -- (16 km) 1,000 to 3,000 miles Length hour (90-400 km/h) he atmosphere is a dynamic system. Temperature changes and the Earth's (1,610-4,850 km) motion are responsible for horizontal and vertical air displacement. Here Polar jet Width 1 to 3 miles 6 miles Jet stream stream (1.6-4.8 km) (10 km) T the air of the atmosphere circulates between the poles and the Equator in horizontal bands within different latitudes. Moreover, the characteristics Discovered in the 19th TROPOSPHERE of the Earth's surface alter the path of the moving air, causing zones of -- century through the use of kites. Airplanes can shorten differing air densities. The relations that arise among these processes their flying time by hitching EARTH'S influence the climatic conditions of our planet. a ride on them. Their paths SURFACE are observed to help predict the weather. Subtropical jet stream + + Rotation of CORIOLIS FORCE the Earth The Coriolis effect is an apparent deflection FERREL CELL of the path of an object that moves within a A part of the air in the HADLEY CELL rotating coordinate system. The Coriolis Hadley cells follows its Warm air ascends in the equatorial region effect appears to deflect the trajectory of course toward the poles and moves toward the middle latitudes, in the winds that move over the surface of the to a latitude of 60° N which the Sun's average angle of incidence is Equator Earth, because the Earth moves beneath the and 60° S. lower than in the tropics. winds. This apparent deflection is to the Intertropical Equator right in the Northern Hemisphere and to the Convergence -- -- left in the Southern Hemisphere. The effect Zone (ITCZ) is only noticeable on a large scale because of WEATHER SYSTEMS ANALYSIS the rotational velocity of the Earth. The continuous lines are isobars (in this case, in the Southern Hemisphere), imaginary lines that connect points of equal pressure. They show depressions— centers of low pressure relative to the surroundings— TRADE WINDS High and Low Pressure These winds blow and an anticyclone, a center of high pressure. toward the Equator. + + Warm air rises and causes a low-pressure area (cyclone) to form beneath it. As the air cools and descends, it forms a high-pressure area (anticyclone). Here the air moves from an -- Low-pressure anticyclonic toward a cyclonic area as wind. The 6 area warm air, as it is displaced and forced upward, leads to the formation of clouds. The masses of High-pressure cold air lose + area their mobility. -- -- 1 Jet-stream Masses of cold currents air descend and Westerlies prevent clouds from forming. 5 The rising air -- + -- Polar leads to the formation of easterlies Isobars Wind clouds. direction Changes in Circulation High-altitude Convergence Divergence Convergence Divergence Minimum wind velocity Maximum wind velocity Jet stream (convergence) (divergence) Irregularities in the topography of the air flow surface, abrupt changes in temperature, (jet stream) The wind blows and the influence of ocean currents can alter 3 from a high- toward the general circulation of the atmosphere. a low-pressure area. These circumstances can generate waves in the B air currents that are, in general, linked to the Surface Anticyclone Cyclone Anticyclone Cyclone cyclonic zones. It is in these zones that storms A 4 originate, and they are therefore studied with air flow great interest. However, the anticyclone and the cyclone systems must be studied together Forces in the upper-air currents, along with The waves in the upper layers The velocity creates a The jet stream The descending air Warm air rises and 2 forms an area of high forms an area of low because cyclones are fed by currents of air surface conditions, may cause air currents to are translated into cyclones and difference in air concentration generates air rotation, pressure (anticyclone). pressure (cyclone). coming from anticyclones. flow together or may split them apart. anticyclones at ground level. between different systems. or vorticity. PDF电子书基地 http://dayo1982.400gb.com
12 CLIMATOLOGY WEATHER AND CLIMATE 13 Atmospheric Dynamics + POLAR CELL JET STREAM 10 miles STRATOSPHERE At the poles, cold air descends Velocity 55 to 250 miles per and moves toward the Equator. -- -- (16 km) 1,000 to 3,000 miles Length hour (90-400 km/h) he atmosphere is a dynamic system. Temperature changes and the Earth's (1,610-4,850 km) motion are responsible for horizontal and vertical air displacement. Here Polar jet Width 1 to 3 miles 6 miles Jet stream stream (1.6-4.8 km) (10 km) T the air of the atmosphere circulates between the poles and the Equator in horizontal bands within different latitudes. Moreover, the characteristics Discovered in the 19th TROPOSPHERE of the Earth's surface alter the path of the moving air, causing zones of -- century through the use of kites. Airplanes can shorten differing air densities. The relations that arise among these processes their flying time by hitching EARTH'S influence the climatic conditions of our planet. a ride on them. Their paths SURFACE are observed to help predict the weather. Subtropical jet stream + + Rotation of CORIOLIS FORCE the Earth The Coriolis effect is an apparent deflection FERREL CELL of the path of an object that moves within a A part of the air in the HADLEY CELL rotating coordinate system. The Coriolis Hadley cells follows its Warm air ascends in the equatorial region effect appears to deflect the trajectory of course toward the poles and moves toward the middle latitudes, in the winds that move over the surface of the to a latitude of 60° N which the Sun's average angle of incidence is Equator Earth, because the Earth moves beneath the and 60° S. lower than in the tropics. winds. This apparent deflection is to the Intertropical Equator right in the Northern Hemisphere and to the Convergence -- -- left in the Southern Hemisphere. The effect Zone (ITCZ) is only noticeable on a large scale because of WEATHER SYSTEMS ANALYSIS the rotational velocity of the Earth. The continuous lines are isobars (in this case, in the Southern Hemisphere), imaginary lines that connect points of equal pressure. They show depressions— centers of low pressure relative to the surroundings— TRADE WINDS High and Low Pressure These winds blow and an anticyclone, a center of high pressure. toward the Equator. + + Warm air rises and causes a low-pressure area (cyclone) to form beneath it. As the air cools and descends, it forms a high-pressure area (anticyclone). Here the air moves from an -- Low-pressure anticyclonic toward a cyclonic area as wind. The 6 area warm air, as it is displaced and forced upward, leads to the formation of clouds. The masses of High-pressure cold air lose + area their mobility. -- -- 1 Jet-stream Masses of cold currents air descend and Westerlies prevent clouds from forming. 5 The rising air -- + -- Polar leads to the formation of easterlies Isobars Wind clouds. direction Changes in Circulation High-altitude Convergence Divergence Convergence Divergence Minimum wind velocity Maximum wind velocity Jet stream (convergence) (divergence) Irregularities in the topography of the air flow surface, abrupt changes in temperature, (jet stream) The wind blows and the influence of ocean currents can alter 3 from a high- toward the general circulation of the atmosphere. a low-pressure area. These circumstances can generate waves in the B air currents that are, in general, linked to the Surface Anticyclone Cyclone Anticyclone Cyclone cyclonic zones. It is in these zones that storms A 4 originate, and they are therefore studied with air flow great interest. However, the anticyclone and the cyclone systems must be studied together Forces in the upper-air currents, along with The waves in the upper layers The velocity creates a The jet stream The descending air Warm air rises and 2 forms an area of high forms an area of low because cyclones are fed by currents of air surface conditions, may cause air currents to are translated into cyclones and difference in air concentration generates air rotation, pressure (anticyclone). pressure (cyclone). coming from anticyclones. flow together or may split them apart. anticyclones at ground level. between different systems. or vorticity. PDF电子书基地 http://dayo1982.400gb.com
14 CLIMATOLOGY WEATHER AND CLIMATE 15 Collision Entire Continents BELARUS Fronts stretch over large geographic areas. GERMANY POLAND hen two air masses with different temperatures and moisture content collide, they STATIONARY FRONTS In this case, a cold front causes storm Kiev perturbations in western Europe. But to the cause atmospheric disturbances. When the warm air rises, its cooling causes water These fronts occur when there is no east, a warm front, extending over a wide FRANCE Bonn Prague Kraków UKRAINE forward motion of warm or cold air—that W vapor to condense and the formation of clouds and precipitation. A mass of warm is, both masses of air are stationary. This area of Poland, brings light rain. These fronts can gain or lose force as they move over the and light air is always forced upward, while the colder and heavier air acts like a wedge. This type of condition can last many days and Earth's surface depending on the global produces only altocumulus clouds. The cold-air wedge undercuts the warmer air mass and forces it to rise more rapidly. temperature also remains stable, and there pressure system. This effect can cause variable, sometimes stormy, weather. is no wind except for some flow of air parallel to the line of the front. There could be some light precipitation. 125 miles KEY Cold Fronts Very dense clouds Cold air Warm air (200 km) Surface cold front Surface warm front These fronts occur when cold air is moved by the that rise to a wind and collides with warmer air. Warm air is considerable altitude A warm front can be 125 miles (200 km) driven upward. The water vapor contained in the air forms Cold front Warm front long. A cold front usually covers about Warm Fronts cumulus clouds, which are rising, dense white clouds. Cold Cool air 60 miles (100 km). In both cases, the fronts can cause the temperature to drop by 10° to 30° F altitude is roughly 0.6 mile (1 km). These are formed by the action of winds. A (about 5°-15° C) and are characterized by violent and mass of warm air occupies a place formerly irregular winds. Their collision with the mass of ascending occupied by a mass of cold air. The speed of the cold water vapor will generate rain, snow flurries, and snow. If air mass, which is heavier, decreases at ground level the condensation is rapid, heavy downpours, snowstorms Cold front Warm air by friction, through contact with the ground. The (during the cold months), and hail may result. In weather warm front ascends and slides above the cold mass. maps, the symbol for a cold front is a blue line of This typically causes precipitation at ground level. triangles indicating the direction of motion. OCCLUDED FRONTS Light rain, snow, or sleet are typically produced, with Cold air Warm air Cool air When the cold air replaces the cool air relatively light winds. The first indications of warm at the surface, with a warm air mass Cold air fronts are cirrus clouds, some 600 miles (1,000 km) in above, a cold occlusion is formed. A front of the advancing low pressure center. Next, warm occlusion occurs when the cool air layers of stratified clouds, such as the cirrostratus, rises above the cold air. These fronts are altostratus, and nimbostratus, are formed while the associated with rain or snow, cumulus Cool air pressure is decreasing. clouds, slight temperature fluctuations, and light winds. Severe imbalance in the cold front A barely noticeable Thick rain The cold front forces the warm clouds Rain below imbalance of a warm front air upward, causing storms. the front Behind the cold front, the sky clears and the temperature drops. There could be precipitation in the area with warm weather. Rossby Waves 1 A long Rossby wave develops 2 The Coriolis effect 3 The formation of a meander of warm in the jet stream of the high and cold air can provide the conditions accentuates the wave action Large horizontal atmospheric waves that are troposphere. in the polar air current. needed to generate cyclones. associated with the polar-front jet stream. If the They may appear as large undulations in the warm front path of the jet stream. The dynamics of the moves faster than climatic system are affected by these waves As the clouds extend The mass of cold air takes the form the retreating wedge of because they promote the exchange of over a region, they of a retreating wedge, which has cold air, the height of the energy between the low and high latitudes produce light rain the effect of lifting the warm air as advancing warm front and can even cause cyclones to form. or snow. it moves over the mass of cold air. continues to increase. PDF电子书基地 http://dayo1982.400gb.com
14 CLIMATOLOGY WEATHER AND CLIMATE 15 Collision Entire Continents BELARUS Fronts stretch over large geographic areas. GERMANY POLAND hen two air masses with different temperatures and moisture content collide, they STATIONARY FRONTS In this case, a cold front causes storm Kiev perturbations in western Europe. But to the cause atmospheric disturbances. When the warm air rises, its cooling causes water These fronts occur when there is no east, a warm front, extending over a wide FRANCE Bonn Prague Kraków UKRAINE forward motion of warm or cold air—that W vapor to condense and the formation of clouds and precipitation. A mass of warm is, both masses of air are stationary. This area of Poland, brings light rain. These fronts can gain or lose force as they move over the and light air is always forced upward, while the colder and heavier air acts like a wedge. This type of condition can last many days and Earth's surface depending on the global produces only altocumulus clouds. The cold-air wedge undercuts the warmer air mass and forces it to rise more rapidly. temperature also remains stable, and there pressure system. This effect can cause variable, sometimes stormy, weather. is no wind except for some flow of air parallel to the line of the front. There could be some light precipitation. 125 miles KEY Cold Fronts Very dense clouds Cold air Warm air (200 km) Surface cold front Surface warm front These fronts occur when cold air is moved by the that rise to a wind and collides with warmer air. Warm air is considerable altitude A warm front can be 125 miles (200 km) driven upward. The water vapor contained in the air forms Cold front Warm front long. A cold front usually covers about Warm Fronts cumulus clouds, which are rising, dense white clouds. Cold Cool air 60 miles (100 km). In both cases, the fronts can cause the temperature to drop by 10° to 30° F altitude is roughly 0.6 mile (1 km). These are formed by the action of winds. A (about 5°-15° C) and are characterized by violent and mass of warm air occupies a place formerly irregular winds. Their collision with the mass of ascending occupied by a mass of cold air. The speed of the cold water vapor will generate rain, snow flurries, and snow. If air mass, which is heavier, decreases at ground level the condensation is rapid, heavy downpours, snowstorms Cold front Warm air by friction, through contact with the ground. The (during the cold months), and hail may result. In weather warm front ascends and slides above the cold mass. maps, the symbol for a cold front is a blue line of This typically causes precipitation at ground level. triangles indicating the direction of motion. OCCLUDED FRONTS Light rain, snow, or sleet are typically produced, with Cold air Warm air Cool air When the cold air replaces the cool air relatively light winds. The first indications of warm at the surface, with a warm air mass Cold air fronts are cirrus clouds, some 600 miles (1,000 km) in above, a cold occlusion is formed. A front of the advancing low pressure center. Next, warm occlusion occurs when the cool air layers of stratified clouds, such as the cirrostratus, rises above the cold air. These fronts are altostratus, and nimbostratus, are formed while the associated with rain or snow, cumulus Cool air pressure is decreasing. clouds, slight temperature fluctuations, and light winds. Severe imbalance in the cold front A barely noticeable Thick rain The cold front forces the warm clouds Rain below imbalance of a warm front air upward, causing storms. the front Behind the cold front, the sky clears and the temperature drops. There could be precipitation in the area with warm weather. Rossby Waves 1 A long Rossby wave develops 2 The Coriolis effect 3 The formation of a meander of warm in the jet stream of the high and cold air can provide the conditions accentuates the wave action Large horizontal atmospheric waves that are troposphere. in the polar air current. needed to generate cyclones. associated with the polar-front jet stream. If the They may appear as large undulations in the warm front path of the jet stream. The dynamics of the moves faster than climatic system are affected by these waves As the clouds extend The mass of cold air takes the form the retreating wedge of because they promote the exchange of over a region, they of a retreating wedge, which has cold air, the height of the energy between the low and high latitudes produce light rain the effect of lifting the warm air as advancing warm front and can even cause cyclones to form. or snow. it moves over the mass of cold air. continues to increase. PDF电子书基地 http://dayo1982.400gb.com
16 CLIMATOLOGY WEATHER AND CLIMATE 17 Colors in the Sky How They Are Produced 620miles The auroras are the result of depending on the altitude at which natural spectacle of incomparable beauty, the auroras are the shock produced as ions they are produced. Moreover, they (1,000 km) produced around the magnetic poles of the Earth by the activity coming from the Sun make contact demonstrate the function of the is how long an aurora can be. magnetosphere, which protects the with the magnetic field of the Earth. A of the Sun. Solar wind acts on the magnetosphere, which is a NORTH POLE They appear in different colors planet against solar winds. From space it will look like a part of the exosphere. In general, the greater the solar wind, the more circle around one of the magnetic poles of the Earth. prominent the aurora. Auroras consist of luminous patches and columns of various colors. Depending on whether they appear in the north or south, they are called aurora borealis or aurora australis. The aurora Sodium atoms Nitrogen atoms and molecules borealis can be seen in Alaska, Canada, and the Scandinavian countries. emit a yellowish and molecules orange light. emit violet light. A satellite image of the aurora borealis 310-370 MILES (500-600 KM) Oxygen atoms MAGNETOSPHERE and molecules (EXOSPHERE) emit green light. 0-6 MILES (0-10 KM) TROPOSPHERE 55-300 MILES (90-500 KM) MESOSPHERE ELECTRONS COLLIDE WITH THEY BECOME THEY GENERATE LIGHT 1 2 3 Depending on the altitude and the MOLECULES EXCITED The oxygen and nitrogen molecules After the shock, the atoms velocity where the shock is produced, receive the impact of the particles receive a significant the aurora displays different colors. from the Sun. This occurs in the additional energetic charge Among the possibilities are violet, magnetosphere (exosphere). that will be released in the green, orange, and yellow. form of photons (light). 10-20 minutes Solar Winds The Sun emits radiation, continuously and BOW SHOCK WAVE THE SUN THE EARTH THE POLES duration of the in all directions. This radiation occurs as a emits solar The Earth's The auroras are more flow of charged particles or plasma, which winds, which magnetosphere is noticeable near the poles; phenomenon consists mainly of electrons and protons. The SOLAR WIND cause serious responsible for they are called aurora plasma particles are guided by the magnetic damage and an protecting the borealis in the Northern The amount of light emitted field of the Sun and form the solar wind, which increase in planet from the Hemisphere and aurora oscillates between 1 and 10 million travels through space at some 275 miles per temperature. deadly and harmful australis in the Southern megawatts, equivalent to the second (450 km/s). Particles from the solar solar winds. Hemisphere. energy produced by 1,000 to wind arrive at the Earth within four or five days. MAGNETOTAIL OVAL AURORA 10,000 large electric power plants. PDF电子书基地 http://dayo1982.400gb.com
16 CLIMATOLOGY WEATHER AND CLIMATE 17 Colors in the Sky How They Are Produced 620miles The auroras are the result of depending on the altitude at which natural spectacle of incomparable beauty, the auroras are the shock produced as ions they are produced. Moreover, they (1,000 km) produced around the magnetic poles of the Earth by the activity coming from the Sun make contact demonstrate the function of the is how long an aurora can be. magnetosphere, which protects the with the magnetic field of the Earth. A of the Sun. Solar wind acts on the magnetosphere, which is a NORTH POLE They appear in different colors planet against solar winds. From space it will look like a part of the exosphere. In general, the greater the solar wind, the more circle around one of the magnetic poles of the Earth. prominent the aurora. Auroras consist of luminous patches and columns of various colors. Depending on whether they appear in the north or south, they are called aurora borealis or aurora australis. The aurora Sodium atoms Nitrogen atoms and molecules borealis can be seen in Alaska, Canada, and the Scandinavian countries. emit a yellowish and molecules orange light. emit violet light. A satellite image of the aurora borealis 310-370 MILES (500-600 KM) Oxygen atoms MAGNETOSPHERE and molecules (EXOSPHERE) emit green light. 0-6 MILES (0-10 KM) TROPOSPHERE 55-300 MILES (90-500 KM) MESOSPHERE ELECTRONS COLLIDE WITH THEY BECOME THEY GENERATE LIGHT 1 2 3 Depending on the altitude and the MOLECULES EXCITED The oxygen and nitrogen molecules After the shock, the atoms velocity where the shock is produced, receive the impact of the particles receive a significant the aurora displays different colors. from the Sun. This occurs in the additional energetic charge Among the possibilities are violet, magnetosphere (exosphere). that will be released in the green, orange, and yellow. form of photons (light). 10-20 minutes Solar Winds The Sun emits radiation, continuously and BOW SHOCK WAVE THE SUN THE EARTH THE POLES duration of the in all directions. This radiation occurs as a emits solar The Earth's The auroras are more flow of charged particles or plasma, which winds, which magnetosphere is noticeable near the poles; phenomenon consists mainly of electrons and protons. The SOLAR WIND cause serious responsible for they are called aurora plasma particles are guided by the magnetic damage and an protecting the borealis in the Northern The amount of light emitted field of the Sun and form the solar wind, which increase in planet from the Hemisphere and aurora oscillates between 1 and 10 million travels through space at some 275 miles per temperature. deadly and harmful australis in the Southern megawatts, equivalent to the second (450 km/s). Particles from the solar solar winds. Hemisphere. energy produced by 1,000 to wind arrive at the Earth within four or five days. MAGNETOTAIL OVAL AURORA 10,000 large electric power plants. PDF电子书基地 http://dayo1982.400gb.com
Surface Factors VIETNAM, DECEMBER 1991 LIVING WATER 20-21 MONSOONS 28-29 The intense monsoon rains GOOD FORTUNE AND CATASTROPHE 30-31 OCEAN CURRENTS 22-23 caused severe flooding in vast regions of Cambodia, Vietnam, AN OBSTACLE COURSE 24-25 THE ARRIVAL OF EL NIÑO 32-33 Laos, and Thailand. THE LAND AND THE OCEAN 26-27 THE EFFECTS OF EL NIÑO 34-35 mong meteorological droughts, lack of food, and an increase in Southwest Asia, there are frequent risk of catching contagious diseases such phenomena, rain plays a very infant mortality. It is clear that an excess typhoons and torrential rains during as malaria. The warm current of El Niño important role in the life of of water, caused by overabundant rain or which millions of people lose their also affects the lives and the economy of humans. Its scarcity causes the effects of gigantic waves, is also houses and must be relocated to more millions of people. A serious problems, such as cause for alarm and concern. In secure areas; however, they still run the PDF电子书基地 http://dayo1982.400gb.com
Surface Factors VIETNAM, DECEMBER 1991 LIVING WATER 20-21 MONSOONS 28-29 The intense monsoon rains GOOD FORTUNE AND CATASTROPHE 30-31 OCEAN CURRENTS 22-23 caused severe flooding in vast regions of Cambodia, Vietnam, AN OBSTACLE COURSE 24-25 THE ARRIVAL OF EL NIÑO 32-33 Laos, and Thailand. THE LAND AND THE OCEAN 26-27 THE EFFECTS OF EL NIÑO 34-35 mong meteorological droughts, lack of food, and an increase in Southwest Asia, there are frequent risk of catching contagious diseases such phenomena, rain plays a very infant mortality. It is clear that an excess typhoons and torrential rains during as malaria. The warm current of El Niño important role in the life of of water, caused by overabundant rain or which millions of people lose their also affects the lives and the economy of humans. Its scarcity causes the effects of gigantic waves, is also houses and must be relocated to more millions of people. A serious problems, such as cause for alarm and concern. In secure areas; however, they still run the PDF电子书基地 http://dayo1982.400gb.com
20 SURFACE FACTORS WEATHER AND CLIMATE 21 Living Water WATER AVAILABILITY Arctic WHERE IT IS FOUND FRESHWATER SALT WATER (cubic feet [cu m] Ocean A small percentage is he water in the oceans, rivers, clouds, and rain is in constant motion. Surface water evaporates, per capita/year) freshwater; most of it 3 % 97 % water in the clouds precipitates, and this precipitation runs along and seeps into the Earth. Less than 60,000 cu ft North Europe Asia is salt water. T Nonetheless, the total amount of water on the planet does not change. The circulation and (1,700 cu m) America Atlantic FRESHWATER Lakes 60,000-175,000 cu ft conservation of water is driven by the hydrologic, or water, cycle. This cycle begins with evaporation of (1,700-5,000 cu m) Ocean Pacific Underground 0.029% water from the Earth's surface. The water vapor humidifies as the air rises. The water vapor in the air cools More than 175,000 cu ft Pacific Ocean water 0.03% Atmosphere (5,000 cu m) 0.001% 1% water on and condenses onto solid particles as microdroplets. The microdroplets combine to form clouds. When the Access to potable water Ocean Africa Indian the surface Ocean Rivers and in the droplets become large enough, they begin to fall back to Earth, and, depending on the temperature of the Less than 50% of the South Oceania Ice atmosphere 0.00015% 2% atmosphere, they return to the ground as rain, snow, or hail. population America EVAPORATION TRANSPIRATION CONDENSATION PRECIPITATION Thanks to the effects of the Perspiration is a natural process In order for water vapor to condense The wind carries the clouds toward the LIQUID STATE SOLID STATE 1. Sun, ocean water is warmed that regulates body temperature. 2. and form clouds, the air must contain 3. continent. When the humid air cools, it A rise in temperature increases the The molecules have very little kinetic energy of the molecules, mobility because of the great and fills the air with water When the body temperature condensation nuclei, which allow the condenses and falls as rain, snow, or hail. which breaks the hydrogen bonds. number of bonds they establish vapor. Evaporation from rises, the sweat glands are molecules of water to form with hydrogen atoms. They humid soil and vegetation stimulated, causing perspiration. microdroplets. For condensation to cubic Some of the molecules form snow crystals. increases humidity. The result occur, the water must be cooled. are set free. is the formation of clouds. CONTRIBUTION OF LIVING 72 miles SNOW BEINGS, ESPECIALLY PLANTS, TO FORMATION OF DROPLETS The majority of The molecules of water them remain THE WATER THE HUMAN vapor decrease their OF WATER FALL EACH DAY IN bonded. IN THE BODY IS mobility and begin THE FORM OF PRECIPITATION. 10% ATMOSPHERE 65% WATER. to collect on solid particles suspended Nucleus GASEOUS STATE in the air. The rays of the Sun RAIN increase the motion The water vapor of atmospheric gases. 3 escapes via The combination of micropores in the heat and wind transforms liquid water leaves' surface. into water vapor. The water ascends 2 via the stem. WIND 1 The root absorbs water. CLOUDS All the Root cells LAKE PERMEABLE molecules LAYERS of water are freed. INFILTRATION Underground aquifers IMPERMEABLE LAYERS AQUIFERS RIVER UNDERGROUND CIRCULATION 300 RUNOFF There are two kinds, both of Water in liquid form runs off 5. which are gravity driven. The 4. the surface of the terrain via OCEAN years first occurs in a shallow zone, in rivers and valleys. In climates karstic rock such as limestone, that are not especially dry, this cubic phenomenon is the principal RETURN TO THE OCEAN and consists of a downward flow. THE AVERAGE LENGTH OF geologic agent of erosion and 340 The waters return to the ocean, completing The second occurs in aquifers, TIME THAT A WATER miles 6. the cycle, which can take days for surface where interstitial water fills up MOLECULE REMAINS IN THE transport. Runoff is reduced OF WATER CIRCULATE IN THE DISCHARGE AREA waters and years for underground waters. the pores of a rock. UNDERGROUND AQUIFERS during times of drought. TERRESTRIAL HYDROSPHERE. PDF电子书基地 http://dayo1982.400gb.com
20 SURFACE FACTORS WEATHER AND CLIMATE 21 Living Water WATER AVAILABILITY Arctic WHERE IT IS FOUND FRESHWATER SALT WATER (cubic feet [cu m] Ocean A small percentage is he water in the oceans, rivers, clouds, and rain is in constant motion. Surface water evaporates, per capita/year) freshwater; most of it 3 % 97 % water in the clouds precipitates, and this precipitation runs along and seeps into the Earth. Less than 60,000 cu ft North Europe Asia is salt water. T Nonetheless, the total amount of water on the planet does not change. The circulation and (1,700 cu m) America Atlantic FRESHWATER Lakes 60,000-175,000 cu ft conservation of water is driven by the hydrologic, or water, cycle. This cycle begins with evaporation of (1,700-5,000 cu m) Ocean Pacific Underground 0.029% water from the Earth's surface. The water vapor humidifies as the air rises. The water vapor in the air cools More than 175,000 cu ft Pacific Ocean water 0.03% Atmosphere (5,000 cu m) 0.001% 1% water on and condenses onto solid particles as microdroplets. The microdroplets combine to form clouds. When the Access to potable water Ocean Africa Indian the surface Ocean Rivers and in the droplets become large enough, they begin to fall back to Earth, and, depending on the temperature of the Less than 50% of the South Oceania Ice atmosphere 0.00015% 2% atmosphere, they return to the ground as rain, snow, or hail. population America EVAPORATION TRANSPIRATION CONDENSATION PRECIPITATION Thanks to the effects of the Perspiration is a natural process In order for water vapor to condense The wind carries the clouds toward the LIQUID STATE SOLID STATE 1. Sun, ocean water is warmed that regulates body temperature. 2. and form clouds, the air must contain 3. continent. When the humid air cools, it A rise in temperature increases the The molecules have very little kinetic energy of the molecules, mobility because of the great and fills the air with water When the body temperature condensation nuclei, which allow the condenses and falls as rain, snow, or hail. which breaks the hydrogen bonds. number of bonds they establish vapor. Evaporation from rises, the sweat glands are molecules of water to form with hydrogen atoms. They humid soil and vegetation stimulated, causing perspiration. microdroplets. For condensation to cubic Some of the molecules form snow crystals. increases humidity. The result occur, the water must be cooled. are set free. is the formation of clouds. CONTRIBUTION OF LIVING 72 miles SNOW BEINGS, ESPECIALLY PLANTS, TO FORMATION OF DROPLETS The majority of The molecules of water them remain THE WATER THE HUMAN vapor decrease their OF WATER FALL EACH DAY IN bonded. IN THE BODY IS mobility and begin THE FORM OF PRECIPITATION. 10% ATMOSPHERE 65% WATER. to collect on solid particles suspended Nucleus GASEOUS STATE in the air. The rays of the Sun RAIN increase the motion The water vapor of atmospheric gases. 3 escapes via The combination of micropores in the heat and wind transforms liquid water leaves' surface. into water vapor. The water ascends 2 via the stem. WIND 1 The root absorbs water. CLOUDS All the Root cells LAKE PERMEABLE molecules LAYERS of water are freed. INFILTRATION Underground aquifers IMPERMEABLE LAYERS AQUIFERS RIVER UNDERGROUND CIRCULATION 300 RUNOFF There are two kinds, both of Water in liquid form runs off 5. which are gravity driven. The 4. the surface of the terrain via OCEAN years first occurs in a shallow zone, in rivers and valleys. In climates karstic rock such as limestone, that are not especially dry, this cubic phenomenon is the principal RETURN TO THE OCEAN and consists of a downward flow. THE AVERAGE LENGTH OF geologic agent of erosion and 340 The waters return to the ocean, completing The second occurs in aquifers, TIME THAT A WATER miles 6. the cycle, which can take days for surface where interstitial water fills up MOLECULE REMAINS IN THE transport. Runoff is reduced OF WATER CIRCULATE IN THE DISCHARGE AREA waters and years for underground waters. the pores of a rock. UNDERGROUND AQUIFERS during times of drought. TERRESTRIAL HYDROSPHERE. PDF电子书基地 http://dayo1982.400gb.com
22 SURFACE FACTORS A l a s k a C u r r e a C u r r e n t WEATHER AND CLIMATE 23 North Pacific Current Oya Current Ocean Currents Pacific California Current Current Current Arctic circulating system SUBPOLAR ARCTIC THE FOUR SEASONS OF A LAKE CIRCULATING SYSTEM For the last five decades, Ocean properties of water, lakes cean water moves as waves, tides, and currents. There are Labrador rador these currents have been Because of the physical shown to be undergoing and lagoons have a special two types of currents: surface and deep. The surface dramatic changes. seasonal circulation that O currents, caused by the wind, are great rivers in the ocean. North Atlantic Current Kuroshio ensures the survival of living creatures. They can be some 50 miles (80 km) wide. They have a profound SUMMER effect on the world climate because the water warms up near Gulf Stream Stable summer temperatures the Equator, and currents transfer this heat to higher latitudes. prevent vertical circulation in the body of water of the lagoon. Deep currents are caused by differences in water density. Pacific Summer North Equatorial Countercurrent nt Ocean stratification Fahrenheit Canary Current 75 ° Atlantic Ocean 77 ° THE INFLUENCE OF THE WINDS Equatorial Countercurrent North Equatorial Countercurrent Epilimnion 64 ° 55 ° Equatorial Countercurrent Thermocline 46 ° TIDES AND THE CORIOLIS EFFECT GEOSTROPHIC BALANCE Hypolimnion 43 ° The Coriolis effect, which influences The deflection caused by the Coriolis effect on 41 ° the direction of the winds, drives the the currents is compensated for by pressure North Equatorial Countercurrent t displacement of marine currents. gradients between cyclonic and anticyclonic North Equatorial Countercurrent Equatorial Countercurrent current systems. This effect is called geostrophic balance. AUTUMN Equatorial Countercurrent South Equatorial Current Temperature decrease and High pressure South Equatorial Cu uatorial Current temperature variations generate South Equatorial Current Coriolis Subtropical high- Low pressure a mixing of the surface and deep force pressure center Subpolar low pressure waters. Pressure South Equatorial Current Autumn mixture gradient Peruvian Current Atlantic antic Indian Current 41 ° Winds Ocean ean Agulhas Current Ocean Brazil Benguela Current 46 ° Pacific 46 ° Ocean Western Australia Current 41 ° Currents in the In the Southern Northern Hemisphere, the Falkland Current Hemisphere travel currents travel in a WINTER in a clockwise counterclockwise When the water reaches 39° F direction. direction. West Australian Current (4° C), its density increases. That An Antarctic circulating system Antarctic Circumpolar Current Warm current is how strata of solid water on the surface and liquid water underneath are created. Antarctic Circumpolar Current 32 ° HOW CURRENTS ARE FORMED Cold current Winter mixture Wind and solar In the Southern This slow ascent of deep 35 ° surface currents 1. Hemisphere, coastal winds 2. water is called a surge. This DEEP CURRENTS 37 ° energy produce motion is modified by the push away the surface in the water. water so that cold water Ekman spiral effect. have a vital function of carrying can ascend. oxygen to deep water. This permits Gulf Warm surface EKMAN SPIRAL life to exist in deep water. Stream waters explains why the surface currents and Subsurface waters deep currents are 1 Near Greenland, 2 Warm surface water occupy the space opposite in direction. the North Atlantic from the Gulf Stream SPRING left by the water sinks, and replaces the cold water The characteristics of water once COAST motion of the Wind energy is the colder and that is sinking. again initiate vertical circulation in surface waters. transferred to the water more saline water the lake. Spring temperatures lead in friction layers. Thus, is pushed to this circulation. 64° F (18 °C) the velocity of the southward. surface water increases Spring mix 61° F (16 °C) more than that of the deep water. 57° F (14 °C) 39 ° The Coriolis effect 37 ° 54° F (12 °C) causes the direction of the currents to deviate. The surface currents Ocean conveyor belt travel in the opposite Deep cold direction of the deep Deep Warm Cold 39 ° water currents. layers PDF电子书基地 http://dayo1982.400gb.com
22 SURFACE FACTORS A l a s k a C u r r e a C u r r e n t WEATHER AND CLIMATE 23 North Pacific Current Oya Current Ocean Currents Pacific California Current Current Current Arctic circulating system SUBPOLAR ARCTIC THE FOUR SEASONS OF A LAKE CIRCULATING SYSTEM For the last five decades, Ocean properties of water, lakes cean water moves as waves, tides, and currents. There are Labrador rador these currents have been Because of the physical shown to be undergoing and lagoons have a special two types of currents: surface and deep. The surface dramatic changes. seasonal circulation that O currents, caused by the wind, are great rivers in the ocean. North Atlantic Current Kuroshio ensures the survival of living creatures. They can be some 50 miles (80 km) wide. They have a profound SUMMER effect on the world climate because the water warms up near Gulf Stream Stable summer temperatures the Equator, and currents transfer this heat to higher latitudes. prevent vertical circulation in the body of water of the lagoon. Deep currents are caused by differences in water density. Pacific Summer North Equatorial Countercurrent nt Ocean stratification Fahrenheit Canary Current 75 ° Atlantic Ocean 77 ° THE INFLUENCE OF THE WINDS Equatorial Countercurrent North Equatorial Countercurrent Epilimnion 64 ° 55 ° Equatorial Countercurrent Thermocline 46 ° TIDES AND THE CORIOLIS EFFECT GEOSTROPHIC BALANCE Hypolimnion 43 ° The Coriolis effect, which influences The deflection caused by the Coriolis effect on 41 ° the direction of the winds, drives the the currents is compensated for by pressure North Equatorial Countercurrent t displacement of marine currents. gradients between cyclonic and anticyclonic North Equatorial Countercurrent Equatorial Countercurrent current systems. This effect is called geostrophic balance. AUTUMN Equatorial Countercurrent South Equatorial Current Temperature decrease and High pressure South Equatorial Cu uatorial Current temperature variations generate South Equatorial Current Coriolis Subtropical high- Low pressure a mixing of the surface and deep force pressure center Subpolar low pressure waters. Pressure South Equatorial Current Autumn mixture gradient Peruvian Current Atlantic antic Indian Current 41 ° Winds Ocean ean Agulhas Current Ocean Brazil Benguela Current 46 ° Pacific 46 ° Ocean Western Australia Current 41 ° Currents in the In the Southern Northern Hemisphere, the Falkland Current Hemisphere travel currents travel in a WINTER in a clockwise counterclockwise When the water reaches 39° F direction. direction. West Australian Current (4° C), its density increases. That An Antarctic circulating system Antarctic Circumpolar Current Warm current is how strata of solid water on the surface and liquid water underneath are created. Antarctic Circumpolar Current 32 ° HOW CURRENTS ARE FORMED Cold current Winter mixture Wind and solar In the Southern This slow ascent of deep 35 ° surface currents 1. Hemisphere, coastal winds 2. water is called a surge. This DEEP CURRENTS 37 ° energy produce motion is modified by the push away the surface in the water. water so that cold water Ekman spiral effect. have a vital function of carrying can ascend. oxygen to deep water. This permits Gulf Warm surface EKMAN SPIRAL life to exist in deep water. Stream waters explains why the surface currents and Subsurface waters deep currents are 1 Near Greenland, 2 Warm surface water occupy the space opposite in direction. the North Atlantic from the Gulf Stream SPRING left by the water sinks, and replaces the cold water The characteristics of water once COAST motion of the Wind energy is the colder and that is sinking. again initiate vertical circulation in surface waters. transferred to the water more saline water the lake. Spring temperatures lead in friction layers. Thus, is pushed to this circulation. 64° F (18 °C) the velocity of the southward. surface water increases Spring mix 61° F (16 °C) more than that of the deep water. 57° F (14 °C) 39 ° The Coriolis effect 37 ° 54° F (12 °C) causes the direction of the currents to deviate. The surface currents Ocean conveyor belt travel in the opposite Deep cold direction of the deep Deep Warm Cold 39 ° water currents. layers PDF电子书基地 http://dayo1982.400gb.com
24 SURFACE FACTORS WEATHER AND CLIMATE 25 Tundra. Its rate of growth An Obstacle Course MAJOR Rocky 13,000 is slow and only during the VEGETATION summer. Mountains MOUNTAIN RANGES Urals (4,000) Taiga. The vegetation is Alps conifer forest. he mountains are geographical features with a great influence on climate. Winds laden with Mountain Elevation Himalayas 10,000 29,035 feet (8,850 m) Everest moisture collide with these vertical obstacles and have to rise up their slopes to pass over Aconcagua 22,834 feet (6,960 m) Appalachians (3,000) Mixed forest. Made up of deciduous trees and conifers. T them. During the ascent, the air discharges water in the form of precipitation on the Dhaulagiri 26,795 feet (8,167 m) 6,500 27,766 feet (8,463 m) Makalu windward sides, which are humid and have dense vegetation. The air that reaches the leeward Nanga Parbat 26,660 feet (8,126 m) (2,000) Chaparral. Brush with thick and dry leaves. slopes is dry, and the vegetation usually consists of sparse grazing land. Kanchenjunga 28,169 feet (8,586 m) Andes 3,000 Ojos del Salado 22,614 feet (6,893 m) Kilimanjaro 19,340 feet (5,895 m) (1,000) Grazing. Thickets predominate: low, perennial grazing plants with an 0 feet (0 m) herbaceous appearance. The Effect of the Andes Mountains Western slopes Eastern slopes SNOW RAIN DESCENDING receive most of the moisture, which The rays of the Sun fall directly upon HUMID WINDS ASCENT AND CONDENSATION PRECIPITATION Drops of super- The microdroplets WIND leads to the growth of pine and other these areas, making them more arid. trees of coastal mountain ranges. There is little or no vegetation. In the mountains, the predominant Condensation occurs when a mass of air cools A natural barrier forces the cooled water increase in size and 4. A natural 1. winds are moisture-laden and blow in 2. until it reaches the saturation point (relative 3. air to ascend and cool. The combine to fall because of barrier forces gravity. form ice crystals. the direction of the coastal mountains. humidity 100 percent). The dew point rises when result is cloud formation the air to the air becomes saturated as it cools and the and precipitation. When they fall, descend and pressure is held constant. The crystals these drops collide warm up. IN THE CLOUD grow in size. with smaller ones. Temperature (in °F [°C]) Composition Successive Height in Moist adiabatic While they are collisions increase feet (m) 18° F gradient -40 to -4 (-40 to -20) Ice crystals falling, they combine the size of the (-8° C) The temperature with other crystals. drops. 16,400 decreases 1° F (5,000) -4 to 14 (-20 to -10) Supercooled 27° F (0.6° C) for every HOW OBSTACLES WORK HIGH LEVEL OF (-3° C) 300 feet (100 m). water POLLUTION IN 13,000 14 to 32 (-10 to 0) Microdroplets Obstacles, such as buildings, FRONT VIEW Rotational flow SANTIAGO (4,000) 36° F Dew point, or of water trees, and rock formations, Partly because it is (2° C) condensation point decrease the velocity of the the most urbanized 10,000 wind significantly and often and industrialized city (3,000) 54° F Dry adiabatic Greater than 32 (0) Drops of create turbulence around them. of Chile, the capital, (12° C) gradient water Santiago, faces 6,500 The temperature serious pollution (2,000) 72° F declines 1.8° F problems. In addition, (22° C) (1° C) every 300 it is located in a 3,000 feet (100 m). valley with (1,000) PLAN VIEW Flow and counterflow characteristics that 90° F do not help disperse Surface (32° C) the pollution produced by vehicles and factories. ANDES MOUNTAIN RANGE Santiago, has altitudes greater than ARGEN T INA Chile 19,700 feet Viña del Mar (6,000 m). It runs parallel to the Pacific Ocean, from Panama to southern Argentina. TYPES OF It is 4,500 miles (7,240 km) long Valparaíso and 150 miles (241 km) wide. OROGRAPHICAL EFFECTS DRY HUMIDS Area affected by C H I L E Winds Winds precipitation VERY HIGH The most humid area is UNEVEN INTERMEDIATE This is produced on halfway up the slope, MOUNTAINSIDE COASTAL DEPRESSION mountains above on the windward side. The most humid MOUNTAIN RANGE 16,400 feet (5,000 m) area is at the top of This drawing shows CLASSIC SCHEME in height. the leeward slope. the coast and the PACIFIC The more humid zone Andes near Santiago, OCEAN is at the top. Chile, at Uspallata Pass. PDF电子书基地 http://dayo1982.400gb.com
24 SURFACE FACTORS WEATHER AND CLIMATE 25 Tundra. Its rate of growth An Obstacle Course MAJOR Rocky 13,000 is slow and only during the VEGETATION summer. Mountains MOUNTAIN RANGES Urals (4,000) Taiga. The vegetation is Alps conifer forest. he mountains are geographical features with a great influence on climate. Winds laden with Mountain Elevation Himalayas 10,000 29,035 feet (8,850 m) Everest moisture collide with these vertical obstacles and have to rise up their slopes to pass over Aconcagua 22,834 feet (6,960 m) Appalachians (3,000) Mixed forest. Made up of deciduous trees and conifers. T them. During the ascent, the air discharges water in the form of precipitation on the Dhaulagiri 26,795 feet (8,167 m) 6,500 27,766 feet (8,463 m) Makalu windward sides, which are humid and have dense vegetation. The air that reaches the leeward Nanga Parbat 26,660 feet (8,126 m) (2,000) Chaparral. Brush with thick and dry leaves. slopes is dry, and the vegetation usually consists of sparse grazing land. Kanchenjunga 28,169 feet (8,586 m) Andes 3,000 Ojos del Salado 22,614 feet (6,893 m) Kilimanjaro 19,340 feet (5,895 m) (1,000) Grazing. Thickets predominate: low, perennial grazing plants with an 0 feet (0 m) herbaceous appearance. The Effect of the Andes Mountains Western slopes Eastern slopes SNOW RAIN DESCENDING receive most of the moisture, which The rays of the Sun fall directly upon HUMID WINDS ASCENT AND CONDENSATION PRECIPITATION Drops of super- The microdroplets WIND leads to the growth of pine and other these areas, making them more arid. trees of coastal mountain ranges. There is little or no vegetation. In the mountains, the predominant Condensation occurs when a mass of air cools A natural barrier forces the cooled water increase in size and 4. A natural 1. winds are moisture-laden and blow in 2. until it reaches the saturation point (relative 3. air to ascend and cool. The combine to fall because of barrier forces gravity. form ice crystals. the direction of the coastal mountains. humidity 100 percent). The dew point rises when result is cloud formation the air to the air becomes saturated as it cools and the and precipitation. When they fall, descend and pressure is held constant. The crystals these drops collide warm up. IN THE CLOUD grow in size. with smaller ones. Temperature (in °F [°C]) Composition Successive Height in Moist adiabatic While they are collisions increase feet (m) 18° F gradient -40 to -4 (-40 to -20) Ice crystals falling, they combine the size of the (-8° C) The temperature with other crystals. drops. 16,400 decreases 1° F (5,000) -4 to 14 (-20 to -10) Supercooled 27° F (0.6° C) for every HOW OBSTACLES WORK HIGH LEVEL OF (-3° C) 300 feet (100 m). water POLLUTION IN 13,000 14 to 32 (-10 to 0) Microdroplets Obstacles, such as buildings, FRONT VIEW Rotational flow SANTIAGO (4,000) 36° F Dew point, or of water trees, and rock formations, Partly because it is (2° C) condensation point decrease the velocity of the the most urbanized 10,000 wind significantly and often and industrialized city (3,000) 54° F Dry adiabatic Greater than 32 (0) Drops of create turbulence around them. of Chile, the capital, (12° C) gradient water Santiago, faces 6,500 The temperature serious pollution (2,000) 72° F declines 1.8° F problems. In addition, (22° C) (1° C) every 300 it is located in a 3,000 feet (100 m). valley with (1,000) PLAN VIEW Flow and counterflow characteristics that 90° F do not help disperse Surface (32° C) the pollution produced by vehicles and factories. ANDES MOUNTAIN RANGE Santiago, has altitudes greater than ARGEN T INA Chile 19,700 feet Viña del Mar (6,000 m). It runs parallel to the Pacific Ocean, from Panama to southern Argentina. TYPES OF It is 4,500 miles (7,240 km) long Valparaíso and 150 miles (241 km) wide. OROGRAPHICAL EFFECTS DRY HUMIDS Area affected by C H I L E Winds Winds precipitation VERY HIGH The most humid area is UNEVEN INTERMEDIATE This is produced on halfway up the slope, MOUNTAINSIDE COASTAL DEPRESSION mountains above on the windward side. The most humid MOUNTAIN RANGE 16,400 feet (5,000 m) area is at the top of This drawing shows CLASSIC SCHEME in height. the leeward slope. the coast and the PACIFIC The more humid zone Andes near Santiago, OCEAN is at the top. Chile, at Uspallata Pass. PDF电子书基地 http://dayo1982.400gb.com
26 SURFACE FACTORS WEATHER AND CLIMATE 27 The Land and WINDS OF THE MOUNTAINS HEAT ISLANDS Isotherms in a typical city CONTINENTALITY Daily variation of temperatures in the United States AND VALLEYS Cities are complex surfaces. Concrete 81° F and asphalt absorb a large quantity of 81° F 82° F In the interior of a landmass, there is a wide variation of 82° F The air is cooled as it ascends, The Sun heats the soil the Ocean 1 of the valley and the 2 becomes more dense, and heat during sunny days and release it 84° F 84° F daily temperatures, while on 84° F 84° F surrounding air, which descends. Then it heats up during the night. the coasts, the influence of 82° F 82° F ascends by convection. again and repeats the cycle. 84°F 86°F 88° F 90°F 86°F 82° F the ocean reduces this 82°F 90°F 88°F 84°F variation. This continentality emperature distribution and, VALLEY 80% effect is quite noticeable in the United States, Russia, above all, temperature RECENT SNOW India, and Australia. T differences very much depend Continentality index on the distribution of land and water 75% surface. Differences in specific heat SLOPE THICK CLOUDS + ALBEDO - ABSORBED 25% 3-5% Less More -ENERGY moderate the temperatures of regions WET SAND WATER (WHEN close to great masses of water. Water THE SUN IS HIGH) They absorb a significant absorbs heat and releases it more 50% 7-14% amount of heat but remain cool COASTAL BREEZES because much energy is used slowly than the land does, which is LIGHT CLOUDS FORESTS to evaporate the moisture. 1. ON THE LAND why a body of water can heat or cool During the day, the land heats up more rapidly than the ocean. The the environment. Its influence is 15% warm air rises and is replaced by cooler air coming from the sea. unmistakable. Moreover, these ALBEDO OF Factories and vehicles emit differences between the land and the MEADOWS large amounts of heat into LAND Because it is the atmosphere. sea are the cause of the coastal winds. WARM AIR opaque, the heat stays in the In clear weather, the land heats up 1 Cold air currents descend from the surface layers, mountainside toward the floor of which are during the day, which causes the air to the valley, which is still hot. heated and rise rapidly and form a low-pressure The air currents cooled rapidly. zone. This zone draws marine breezes. 2 are heated and ascend by convection. When they rise, they cool and once again descend along the IN THE OCEAN From the coast, the ocean receives mountainside. air that loses its heat near the water. As a result, the colder air MOUNTAINSIDE descends toward the sea. MOUNTAIN WINDS The heat penetrates into COLD AIR Chinook WINDS deeper layers These winds are dry and warm, sometimes quite hot, thanks to the transparency of occurring in various places of the world. In the western the water. A United States, they are called chinooks and are capable VALLEY part of the heat of making snow disappear within minutes. WATER is lost in evaporation of Humid winds are lifted over The dry and cool wind The air tends to the water. the slopes, creating clouds descends down the descend in forested and precipitation on the mountain slope on the and rural areas. windward side. These are leeward side. It is During the night, the city ON THE LAND called anabatic winds. called katabatic. slowly releases heat that was 2. During the evening, the land radiates absorbed during the day. away its heat more rapidly than the water. The difference in pressure generated replaces the cold air of the coast with warm air. LEEWARD The flows tend toward equilibrium. When night COLD AIR falls, the land, WINDWARD which was hot, WARM AIR WHIRLWINDS cools rapidly. LAND Intense heat on the plains can generate a hot, spiral- formed column of air sometimes more than 300 feet (100 m) high. Winds Characteristics Location Autan wind Dry and mild Southwestern France 1 Strong, high-speed winds move on A powerful air IN THE OCEAN Berg Dry and warm South Africa 1 top of weaker winds and cause the 2 current lifts the The loss of heat from the water is Bora Dry and cold Northeastern Italy intermediate air to be displaced like spiral. slower. Brickfielder Dry and hot Australia a pencil on a table. Buran Dry and cold Mongolia Harmattan Dry and cool North Africa WARM AIR Levant Humid and mild Mediterranean region When night Mistral Dry and cold Rhône valley falls, the water Santa Ana Dry and hot Southern California STRONG WIND KEY is lukewarm Sirocco Dry and hot Southern Europe and North Africa (barely a Tramontana Dry and cold Northeast Spain WATER degree more Zonda Dry and mild Western Argentina MILD WIND WARM-AIR COLD-AIR than the land). FLOW FLOW PDF电子书基地 http://dayo1982.400gb.com
26 SURFACE FACTORS WEATHER AND CLIMATE 27 The Land and WINDS OF THE MOUNTAINS HEAT ISLANDS Isotherms in a typical city CONTINENTALITY Daily variation of temperatures in the United States AND VALLEYS Cities are complex surfaces. Concrete 81° F and asphalt absorb a large quantity of 81° F 82° F In the interior of a landmass, there is a wide variation of 82° F The air is cooled as it ascends, The Sun heats the soil the Ocean 1 of the valley and the 2 becomes more dense, and heat during sunny days and release it 84° F 84° F daily temperatures, while on 84° F 84° F surrounding air, which descends. Then it heats up during the night. the coasts, the influence of 82° F 82° F ascends by convection. again and repeats the cycle. 84°F 86°F 88° F 90°F 86°F 82° F the ocean reduces this 82°F 90°F 88°F 84°F variation. This continentality emperature distribution and, VALLEY 80% effect is quite noticeable in the United States, Russia, above all, temperature RECENT SNOW India, and Australia. T differences very much depend Continentality index on the distribution of land and water 75% surface. Differences in specific heat SLOPE THICK CLOUDS + ALBEDO - ABSORBED 25% 3-5% Less More -ENERGY moderate the temperatures of regions WET SAND WATER (WHEN close to great masses of water. Water THE SUN IS HIGH) They absorb a significant absorbs heat and releases it more 50% 7-14% amount of heat but remain cool COASTAL BREEZES because much energy is used slowly than the land does, which is LIGHT CLOUDS FORESTS to evaporate the moisture. 1. ON THE LAND why a body of water can heat or cool During the day, the land heats up more rapidly than the ocean. The the environment. Its influence is 15% warm air rises and is replaced by cooler air coming from the sea. unmistakable. Moreover, these ALBEDO OF Factories and vehicles emit differences between the land and the MEADOWS large amounts of heat into LAND Because it is the atmosphere. sea are the cause of the coastal winds. WARM AIR opaque, the heat stays in the In clear weather, the land heats up 1 Cold air currents descend from the surface layers, mountainside toward the floor of which are during the day, which causes the air to the valley, which is still hot. heated and rise rapidly and form a low-pressure The air currents cooled rapidly. zone. This zone draws marine breezes. 2 are heated and ascend by convection. When they rise, they cool and once again descend along the IN THE OCEAN From the coast, the ocean receives mountainside. air that loses its heat near the water. As a result, the colder air MOUNTAINSIDE descends toward the sea. MOUNTAIN WINDS The heat penetrates into COLD AIR Chinook WINDS deeper layers These winds are dry and warm, sometimes quite hot, thanks to the transparency of occurring in various places of the world. In the western the water. A United States, they are called chinooks and are capable VALLEY part of the heat of making snow disappear within minutes. WATER is lost in evaporation of Humid winds are lifted over The dry and cool wind The air tends to the water. the slopes, creating clouds descends down the descend in forested and precipitation on the mountain slope on the and rural areas. windward side. These are leeward side. It is During the night, the city ON THE LAND called anabatic winds. called katabatic. slowly releases heat that was 2. During the evening, the land radiates absorbed during the day. away its heat more rapidly than the water. The difference in pressure generated replaces the cold air of the coast with warm air. LEEWARD The flows tend toward equilibrium. When night COLD AIR falls, the land, WINDWARD which was hot, WARM AIR WHIRLWINDS cools rapidly. LAND Intense heat on the plains can generate a hot, spiral- formed column of air sometimes more than 300 feet (100 m) high. Winds Characteristics Location Autan wind Dry and mild Southwestern France 1 Strong, high-speed winds move on A powerful air IN THE OCEAN Berg Dry and warm South Africa 1 top of weaker winds and cause the 2 current lifts the The loss of heat from the water is Bora Dry and cold Northeastern Italy intermediate air to be displaced like spiral. slower. Brickfielder Dry and hot Australia a pencil on a table. Buran Dry and cold Mongolia Harmattan Dry and cool North Africa WARM AIR Levant Humid and mild Mediterranean region When night Mistral Dry and cold Rhône valley falls, the water Santa Ana Dry and hot Southern California STRONG WIND KEY is lukewarm Sirocco Dry and hot Southern Europe and North Africa (barely a Tramontana Dry and cold Northeast Spain WATER degree more Zonda Dry and mild Western Argentina MILD WIND WARM-AIR COLD-AIR than the land). FLOW FLOW PDF电子书基地 http://dayo1982.400gb.com
28 SURFACE FACTORS WEATHER AND CLIMATE 29 Monsoons How monsoons are THERMAL The land is cold, so near The sea is a little warmer The Earth is hot, and The sea is cold because the ground the breeze the rays of the Sun heat than the land; therefore, therefore the air rises and created in India DIFFERENCE blows toward the ocean. the humid air rises. The is replaced in the lower up the water more layers by cool breezes that slowly than the land. cool air colliding with it BETWEEN THE LAND The cool air from the causes clouds and rain. blow in from the sea. The he strong humid winds that usually affect AND THE OCEAN meeting of the two breezes ocean blows toward the the tropical zone are called monsoons, an End of the Beginning of Cold and Cold and Cyclone Anticyclone causes clouds and rain on coast, toward areas that are warmer. the continent. T Arabic word meaning “seasonal winds.” monsoon the monsoon dry winds humid (low (high winds pressure) pressure) During summer in the Northern Hemisphere, they Angle of incidence of blow across Southeast Asia, especially the Indian THE CONTINENT COOLS the Sun's rays peninsula. Conditions change in the winter, and the 1 After the summer monsoon, the rains stop and temperatures in Central and South Asia begin to drop. winds reverse and shift toward the northern Winter begins in the Northern Hemisphere. regions of Australia. This phenomenon, which is Northern Hemisphere also frequent in continental areas of the United It is winter. The rays of the Rays of Sun are oblique, traveling a the Sun States, is part of an annual cycle that, as a result longer distance through N the atmosphere to reach of its intensity and its consequences, affects the the Earth's surface. Thus they are spread over a lives of many people. larger surface, so the average temperature is lower than in the Southern Cold land Hemisphere. AREAS AFFECTED BY MONSOONS Southern Hemisphere It is summer. The rays of This phenomenon affects the climates in low latitudes, from Predominant the Sun strike the surface West Africa to the western Pacific. In the summer, the direction of the at a right angle; they are S concentrated in a smaller monsoon causes the rains in the Amazon region and in winds during the area, so the temperature northern Argentina. There in the winter rain is usually scarce. month of July on average is higher than in the Northern Hemisphere. FROM THE CONTINENT 2 TO THE OCEAN The masses of cold and dry air that predominate on the Warm continent are displaced land toward the ocean, whose waters are relatively warmer. Arabian Sea Bay of Bengal Limit of the intertropical THE MONSOON OF NORTH AMERICA convergence Arabian Pre-monsoon. Month of May. Monsoon. Month of July. Sea OCEAN STORMS STORMS ON THE 3 A cyclone located in the ocean draws CONTINENT 3 the cold winds from the continent and The climate in India lifts the somewhat warmer and more and Bangladesh is very humid air, which returns toward the hot and dry. When humid continent via the upper layers of the and cool winds come in from atmosphere. the ocean, they cause torrential rains in these regions. Cross section (enlarged area) Rays of the Sun Limit of the INTERTROPICAL INFLUENCE Intertropical BARRIERS The circulation of the atmosphere between the Convergence Bay of The humid winds are 2 Descent of the air Descent of the air tropics influences the formation of monsoon Zone (ITCZ) Bengal from high altitudes from high altitudes winds. The trade winds that blow toward the deflected toward Equator from the subtropical zones are pushed by FROM THE the northeast by the Hadley cells and deflected in their course by 1 OCEAN TO THE two mountain chains: the Coriolis effect. Winds in the tropics occur CONTINENT the Himalayas and the Transport of Western Sierra Transport of within a band of low pressure around the Earth The cool and humid air Ghat mountains. This zone water vapor Madre water vapor called the Intertropical Convergence Zone (ITCZ). from the ocean blows enclosed by the mountains When this zone is seasonally displaced in the warm months of the Northern Hemisphere toward toward the continent, is the main one affected Pacific Ocean Gulf of California Gulf of Mexico the north, a summer monsoon occurs. which is quite hot and dry. by the monsoons. PDF电子书基地 http://dayo1982.400gb.com
28 SURFACE FACTORS WEATHER AND CLIMATE 29 Monsoons How monsoons are THERMAL The land is cold, so near The sea is a little warmer The Earth is hot, and The sea is cold because the ground the breeze the rays of the Sun heat than the land; therefore, therefore the air rises and created in India DIFFERENCE blows toward the ocean. the humid air rises. The is replaced in the lower up the water more layers by cool breezes that slowly than the land. cool air colliding with it BETWEEN THE LAND The cool air from the causes clouds and rain. blow in from the sea. The he strong humid winds that usually affect AND THE OCEAN meeting of the two breezes ocean blows toward the the tropical zone are called monsoons, an End of the Beginning of Cold and Cold and Cyclone Anticyclone causes clouds and rain on coast, toward areas that are warmer. the continent. T Arabic word meaning “seasonal winds.” monsoon the monsoon dry winds humid (low (high winds pressure) pressure) During summer in the Northern Hemisphere, they Angle of incidence of blow across Southeast Asia, especially the Indian THE CONTINENT COOLS the Sun's rays peninsula. Conditions change in the winter, and the 1 After the summer monsoon, the rains stop and temperatures in Central and South Asia begin to drop. winds reverse and shift toward the northern Winter begins in the Northern Hemisphere. regions of Australia. This phenomenon, which is Northern Hemisphere also frequent in continental areas of the United It is winter. The rays of the Rays of Sun are oblique, traveling a the Sun States, is part of an annual cycle that, as a result longer distance through N the atmosphere to reach of its intensity and its consequences, affects the the Earth's surface. Thus they are spread over a lives of many people. larger surface, so the average temperature is lower than in the Southern Cold land Hemisphere. AREAS AFFECTED BY MONSOONS Southern Hemisphere It is summer. The rays of This phenomenon affects the climates in low latitudes, from Predominant the Sun strike the surface West Africa to the western Pacific. In the summer, the direction of the at a right angle; they are S concentrated in a smaller monsoon causes the rains in the Amazon region and in winds during the area, so the temperature northern Argentina. There in the winter rain is usually scarce. month of July on average is higher than in the Northern Hemisphere. FROM THE CONTINENT 2 TO THE OCEAN The masses of cold and dry air that predominate on the Warm continent are displaced land toward the ocean, whose waters are relatively warmer. Arabian Sea Bay of Bengal Limit of the intertropical THE MONSOON OF NORTH AMERICA convergence Arabian Pre-monsoon. Month of May. Monsoon. Month of July. Sea OCEAN STORMS STORMS ON THE 3 A cyclone located in the ocean draws CONTINENT 3 the cold winds from the continent and The climate in India lifts the somewhat warmer and more and Bangladesh is very humid air, which returns toward the hot and dry. When humid continent via the upper layers of the and cool winds come in from atmosphere. the ocean, they cause torrential rains in these regions. Cross section (enlarged area) Rays of the Sun Limit of the INTERTROPICAL INFLUENCE Intertropical BARRIERS The circulation of the atmosphere between the Convergence Bay of The humid winds are 2 Descent of the air Descent of the air tropics influences the formation of monsoon Zone (ITCZ) Bengal from high altitudes from high altitudes winds. The trade winds that blow toward the deflected toward Equator from the subtropical zones are pushed by FROM THE the northeast by the Hadley cells and deflected in their course by 1 OCEAN TO THE two mountain chains: the Coriolis effect. Winds in the tropics occur CONTINENT the Himalayas and the Transport of Western Sierra Transport of within a band of low pressure around the Earth The cool and humid air Ghat mountains. This zone water vapor Madre water vapor called the Intertropical Convergence Zone (ITCZ). from the ocean blows enclosed by the mountains When this zone is seasonally displaced in the warm months of the Northern Hemisphere toward toward the continent, is the main one affected Pacific Ocean Gulf of California Gulf of Mexico the north, a summer monsoon occurs. which is quite hot and dry. by the monsoons. PDF电子书基地 http://dayo1982.400gb.com
30 SURFACE FACTORS WEATHER AND CLIMATE 31 Good Fortune and Catastrophe In June 2006 INDIA AND The tragic outcome of the BANGLADESH Total population monsoon in South Asia 1.25 billion he monsoons are a climatic phenomenon governing the life and the economy of one of the most Uttaranchal densely populated regions of the planet, especially India. The arrival of the intense rains is ~49 T celebrated as the end of a season that might have been extremely dry, but it is also feared. The DEATHS Nueva Delhi on June 16, 2006 flooding at times devastates agriculture and housing. The damage is even greater because of the large population of the region. Therefore, anticipating disaster and taking precautions, such as evacuating areas prone to flooding, are part of the organization of agricultural activity, Precipitation BANGLADESH (in inches [mm]) which thrives in periods of heavy rains, even in fields that are flooded. INDIA 16 (400) Extreme humidity Dhaka 8 (200) 4 (100) Very humid ~1 million 2 (50) Humid PEOPLE STRANDED BY STORMS 1 (25) Normal IN BANGLADESH 0.4 (10) Very dry 21 Kerala DEATHS IN 0.04 (1) Extremely ~212 INDIA DEATHS During the month of June 2006. dry On June 16, Most of them were electrocuted by 0 (0) 2006 lightning during electrical storms. OVERFLOWING RIVERS The valley that connects the Ganges with the Brahmaputra in Bangladesh is the most UNDERWATER HARVEST afflicted by floods caused by The mud increases the fertility these rains. The rains destroy of the soil, which compensates harvests and property. for the losses. The accumulation of humid sand is later used in the dry season. Rice is a grain that grows in fields that are underwater. PDF电子书基地 http://dayo1982.400gb.com
30 SURFACE FACTORS WEATHER AND CLIMATE 31 Good Fortune and Catastrophe In June 2006 INDIA AND The tragic outcome of the BANGLADESH Total population monsoon in South Asia 1.25 billion he monsoons are a climatic phenomenon governing the life and the economy of one of the most Uttaranchal densely populated regions of the planet, especially India. The arrival of the intense rains is ~49 T celebrated as the end of a season that might have been extremely dry, but it is also feared. The DEATHS Nueva Delhi on June 16, 2006 flooding at times devastates agriculture and housing. The damage is even greater because of the large population of the region. Therefore, anticipating disaster and taking precautions, such as evacuating areas prone to flooding, are part of the organization of agricultural activity, Precipitation BANGLADESH (in inches [mm]) which thrives in periods of heavy rains, even in fields that are flooded. INDIA 16 (400) Extreme humidity Dhaka 8 (200) 4 (100) Very humid ~1 million 2 (50) Humid PEOPLE STRANDED BY STORMS 1 (25) Normal IN BANGLADESH 0.4 (10) Very dry 21 Kerala DEATHS IN 0.04 (1) Extremely ~212 INDIA DEATHS During the month of June 2006. dry On June 16, Most of them were electrocuted by 0 (0) 2006 lightning during electrical storms. OVERFLOWING RIVERS The valley that connects the Ganges with the Brahmaputra in Bangladesh is the most UNDERWATER HARVEST afflicted by floods caused by The mud increases the fertility these rains. The rains destroy of the soil, which compensates harvests and property. for the losses. The accumulation of humid sand is later used in the dry season. Rice is a grain that grows in fields that are underwater. PDF电子书基地 http://dayo1982.400gb.com
32 SURFACE FACTORS WEATHER AND CLIMATE 33 The Arrival of El Niño SURFACE TEMPERATURE EL NIÑO Intense OF THE OCEAN Warmer The graphic shows the than normal Average intensity 5.4° F (3° C) he hydrosphere and the atmosphere interact and establish a dynamic thermal equilibrium temperature variations 2° C between the water and the air. If this balance is altered, unusual climatic phenomena occur caused by the Southern NORMAL 1° C Oscillation in the water 0 T between the coasts of Peru and Southeast Asia. For example, the phenomenon El Niño or, less along the coast of Peru. -1° C This graphic illustrates the frequently, another phenomenon called La Niña are responsible for atypical droughts and floods that alternation of the El Niño LA NIÑA -2° C Colder than every two to seven years affect the routine life of people living on these Pacific Ocean coasts. and La Niña phenomena normal over the last 50 years. Normal Conditions KEY El Niño (the warm phase of El La Niña (cold ENSO) Anticyclone (high- Niño/Southern Oscillation [ENSO]) DURATION: 9 to 18 months pressure center) FREQUENCY: Every 2 to 7 years DURATION 9 to 18 months Intertropical Intertropical Convergence A cold current Severe drought Convergence 3 Peru Zone 2 The total disruption of 3 The effects of La Niña are less Peru Zone Current the masses of warm severe than those of El Niño. Current Cold Mild Warm Peru Current water off the west coast Also, the shorter its duration, Intertropical TRADE of South America also the more intense it is. It TRADE Convergence El Niño makes itself felt. WINDS generates colder surface typically begins about halfway WINDS TRADE WINDS Zone Southeast Asia suffers a great (strong) temperatures than through the year and Trade winds (weak) drought, an increase of pressure, normal along with high intensifies at the end of the 3 These relatively constant Anticyclone of and a decrease in temperature. Anticyclone pressure and decreased year before weakening around South winds push the waters of the the South On the South American coast, of the South Anticyclone Pacific Pacific Ocean from east to The anticyclone Atlantic strong winds and storms occur in Pacific of the South humidity. the beginning of the new year. anticyclone of the South Pacific zones that are usually dry; there Atlantic In the Caribbean, La Niña South Atlantic west. Between the coasts of causes an increase in humidity. anticyclone Indonesia and those of is displaced toward is flooding and changes in the western South America, there the south. flora and fauna. is on average a 2 foot (0.5 m) Climate inversion difference in sea level. 2 For six months, the Warm coasts normal climatic Overcompensation 2 Because great masses of warm Without trade winds conditions are reversed. 1 The return of normal conditions after El water permanently flow toward the coasts of Indonesia 1 In periods that can vary The temperature of the Niño can be (although not necessarily) the water and air increases from two to seven years, the preamble to an inverse phenomenon called and New Guinea, they are trade winds that push the along the coasts of Peru La Niña. As a consequence of Southern 1 about 14° F (8° C) warmer warm water toward the west and Ecuador, and the Oscillation pressure levels, the trade than the South American humidity causes can be sharply reduced or even coast, where there is also an fail to occur. As a result, the heavy rains. winds become stronger than normal. upwelling of cold water from Climatic equilibrium the ocean floor. entire mass moves toward the Normally the coasts of South American coast. Southeast Asia lie in an area of low pressure and high humidity, which causes heavy Cold surface precipitation. On the water and deep American coast of the South water Pacific, the climate is very dry by comparison. Warm surface waters Warm surface waters The mass of relatively warm water is displaced completely toward the western Pacific. Cold deep Warm The ascent of the cold water blocks any warm current waters surface water that might go east. Relatively warm waters replace Upwelling the upwelling cold water, which cold water ON A WORLD SCALE typically brings a large amount of varied fish and other marine life to the The temperature of the surface of the ocean surface off the South American coast. during the El Niño phase of 1997 Without this upwelling, fishing output drops off rapidly. Very Cold Normal Cold Warm Hot VIA SATELLITE How the height of sea level changed because of the ENSO phenomenon. A large 5.5 (140) mass of warm 0 (0) water accumulates on the western coasts of the South Inches (mm) -7 (-180) Pacific and is sustained by the Images persistence of the trade winds created by the at the ocean surface. -7 -5.5 -4 -2 -0.08 0.08 2.4 4 5.5 7 TOPEX/Poseidon (-180) (-140) (-100) (-50) (-20) (20) (60) (100) (140) (180) EL NIÑO. April 25, 1997 May 25, 1997 satellite. June 25, 1997 September 5, 1997 LA NIÑA. July 11, 1998 PDF电子书基地 http://dayo1982.400gb.com
32 SURFACE FACTORS WEATHER AND CLIMATE 33 The Arrival of El Niño SURFACE TEMPERATURE EL NIÑO Intense OF THE OCEAN Warmer The graphic shows the than normal Average intensity 5.4° F (3° C) he hydrosphere and the atmosphere interact and establish a dynamic thermal equilibrium temperature variations 2° C between the water and the air. If this balance is altered, unusual climatic phenomena occur caused by the Southern NORMAL 1° C Oscillation in the water 0 T between the coasts of Peru and Southeast Asia. For example, the phenomenon El Niño or, less along the coast of Peru. -1° C This graphic illustrates the frequently, another phenomenon called La Niña are responsible for atypical droughts and floods that alternation of the El Niño LA NIÑA -2° C Colder than every two to seven years affect the routine life of people living on these Pacific Ocean coasts. and La Niña phenomena normal over the last 50 years. Normal Conditions KEY El Niño (the warm phase of El La Niña (cold ENSO) Anticyclone (high- Niño/Southern Oscillation [ENSO]) DURATION: 9 to 18 months pressure center) FREQUENCY: Every 2 to 7 years DURATION 9 to 18 months Intertropical Intertropical Convergence A cold current Severe drought Convergence 3 Peru Zone 2 The total disruption of 3 The effects of La Niña are less Peru Zone Current the masses of warm severe than those of El Niño. Current Cold Mild Warm Peru Current water off the west coast Also, the shorter its duration, Intertropical TRADE of South America also the more intense it is. It TRADE Convergence El Niño makes itself felt. WINDS generates colder surface typically begins about halfway WINDS TRADE WINDS Zone Southeast Asia suffers a great (strong) temperatures than through the year and Trade winds (weak) drought, an increase of pressure, normal along with high intensifies at the end of the 3 These relatively constant Anticyclone of and a decrease in temperature. Anticyclone pressure and decreased year before weakening around South winds push the waters of the the South On the South American coast, of the South Anticyclone Pacific Pacific Ocean from east to The anticyclone Atlantic strong winds and storms occur in Pacific of the South humidity. the beginning of the new year. anticyclone of the South Pacific zones that are usually dry; there Atlantic In the Caribbean, La Niña South Atlantic west. Between the coasts of causes an increase in humidity. anticyclone Indonesia and those of is displaced toward is flooding and changes in the western South America, there the south. flora and fauna. is on average a 2 foot (0.5 m) Climate inversion difference in sea level. 2 For six months, the Warm coasts normal climatic Overcompensation 2 Because great masses of warm Without trade winds conditions are reversed. 1 The return of normal conditions after El water permanently flow toward the coasts of Indonesia 1 In periods that can vary The temperature of the Niño can be (although not necessarily) the water and air increases from two to seven years, the preamble to an inverse phenomenon called and New Guinea, they are trade winds that push the along the coasts of Peru La Niña. As a consequence of Southern 1 about 14° F (8° C) warmer warm water toward the west and Ecuador, and the Oscillation pressure levels, the trade than the South American humidity causes can be sharply reduced or even coast, where there is also an fail to occur. As a result, the heavy rains. winds become stronger than normal. upwelling of cold water from Climatic equilibrium the ocean floor. entire mass moves toward the Normally the coasts of South American coast. Southeast Asia lie in an area of low pressure and high humidity, which causes heavy Cold surface precipitation. On the water and deep American coast of the South water Pacific, the climate is very dry by comparison. Warm surface waters Warm surface waters The mass of relatively warm water is displaced completely toward the western Pacific. Cold deep Warm The ascent of the cold water blocks any warm current waters surface water that might go east. Relatively warm waters replace Upwelling the upwelling cold water, which cold water ON A WORLD SCALE typically brings a large amount of varied fish and other marine life to the The temperature of the surface of the ocean surface off the South American coast. during the El Niño phase of 1997 Without this upwelling, fishing output drops off rapidly. Very Cold Normal Cold Warm Hot VIA SATELLITE How the height of sea level changed because of the ENSO phenomenon. A large 5.5 (140) mass of warm 0 (0) water accumulates on the western coasts of the South Inches (mm) -7 (-180) Pacific and is sustained by the Images persistence of the trade winds created by the at the ocean surface. -7 -5.5 -4 -2 -0.08 0.08 2.4 4 5.5 7 TOPEX/Poseidon (-180) (-140) (-100) (-50) (-20) (20) (60) (100) (140) (180) EL NIÑO. April 25, 1997 May 25, 1997 satellite. June 25, 1997 September 5, 1997 LA NIÑA. July 11, 1998 PDF电子书基地 http://dayo1982.400gb.com
34 SURFACE FACTORS WEATHER AND CLIMATE 35 KEY The Effects of El Niño Areas Affected LA NIÑA from June to August Humid EL NIÑO from December to February Cold he natural warm phenomenon known as El Niño alters the temperature of the water within the Cold Humid east central zone of the Pacific Ocean along the coasts of Ecuador and Peru. Farmers and fishermen ASI A ASI A Warm T are negatively affected by these changes in temperature and the modification of marine currents. AMERICA AMERICA Humid The nutrients normally present in the ocean decrease or disappear from along the coast because of the Warm Humid increase in temperature. As the entire food chain deteriorates, other species also suffer the effects and AFRICA AFRICA disappear from the ocean. In contrast, tropical marine species that live in warmer waters can flourish. Dry The phenomenon affects the weather and climate of the entire world. It tends to cause flooding, food Dry and shortages, droughts, and fires in various locations. OCEANIA OCEANIA cold Dry and warm Normal conditions The phytoplankton promote During El Niño, Various marine species die Cold waters, rich in nutrients, the normal development of the scarcity of cold water off for lack of food or must ascend from the bottom of microorganisms, fish, and debilitates the phytoplankton migrate to other zones. the sea and provide favorable other creatures. population and alters the FLOODING conditions for the growth of marine food chain. Abnormal flooding caused by phytoplankton, the basis of El Niño in the desert regions the marine food chain. of Chile and the later evaporation of water leave behind hexagonal deposits of potassium nitrate. ATACAMA, CHILE Surface area 1,200 square miles (3,000 sq km) Laguna Blanca Cause Floods caused by El Niño Salt Marsh anomalies Latitude 22° 54´ S Year 1999 Longitude 68° 12´ W PDF电子书基地 http://dayo1982.400gb.com
34 SURFACE FACTORS WEATHER AND CLIMATE 35 KEY The Effects of El Niño Areas Affected LA NIÑA from June to August Humid EL NIÑO from December to February Cold he natural warm phenomenon known as El Niño alters the temperature of the water within the Cold Humid east central zone of the Pacific Ocean along the coasts of Ecuador and Peru. Farmers and fishermen ASI A ASI A Warm T are negatively affected by these changes in temperature and the modification of marine currents. AMERICA AMERICA Humid The nutrients normally present in the ocean decrease or disappear from along the coast because of the Warm Humid increase in temperature. As the entire food chain deteriorates, other species also suffer the effects and AFRICA AFRICA disappear from the ocean. In contrast, tropical marine species that live in warmer waters can flourish. Dry The phenomenon affects the weather and climate of the entire world. It tends to cause flooding, food Dry and shortages, droughts, and fires in various locations. OCEANIA OCEANIA cold Dry and warm Normal conditions The phytoplankton promote During El Niño, Various marine species die Cold waters, rich in nutrients, the normal development of the scarcity of cold water off for lack of food or must ascend from the bottom of microorganisms, fish, and debilitates the phytoplankton migrate to other zones. the sea and provide favorable other creatures. population and alters the FLOODING conditions for the growth of marine food chain. Abnormal flooding caused by phytoplankton, the basis of El Niño in the desert regions the marine food chain. of Chile and the later evaporation of water leave behind hexagonal deposits of potassium nitrate. ATACAMA, CHILE Surface area 1,200 square miles (3,000 sq km) Laguna Blanca Cause Floods caused by El Niño Salt Marsh anomalies Latitude 22° 54´ S Year 1999 Longitude 68° 12´ W PDF电子书基地 http://dayo1982.400gb.com
Meteorological HURRICANE ALERT CAPRICIOUS FORMS 38-39 WHEN WATER ACCUMULATES 48-49 ANATOMY OF A HURRICANE 56-57 This image of Hurricane Elena, captured THE RAIN ANNOUNCES ITS COMING 40-43 WATER SCARCITY 50-51 WHAT KATRINA TOOK AWAY 58-59 by the Space Shuttle on September 1, 1985, allowed meteorologists to LOST IN THE FOG 44-45 LETHAL FORCE 52-53 FORESIGHT TO PREVENT TRAGEDIES 60-61 Phenomena evaluate its scope before it reached the BRIEF FLASH 46-47 DEATH AND DESTRUCTION 54-55 Gulf of Mexico. ropical cyclones (called They uproot trees, damage buildings, the government authorities organize require detailed information from the heart hurricanes, typhoons, or cyclones devastate land under cultivation, and preparedness exercises so that the of the storm. The use of artificial satellites in different parts of the world) cause deaths. The Gulf of Mexico is one population knows what to do. To that send clear pictures has contributed cause serious problems and often of the areas of the planet continually understand how hurricanes function greatly to detecting and tracking strong Tdestroy everything in their path. affected by hurricanes. For this reason, and improve forecasts, investigators winds, preventing many disasters. PDF电子书基地 http://dayo1982.400gb.com
Meteorological HURRICANE ALERT CAPRICIOUS FORMS 38-39 WHEN WATER ACCUMULATES 48-49 ANATOMY OF A HURRICANE 56-57 This image of Hurricane Elena, captured THE RAIN ANNOUNCES ITS COMING 40-43 WATER SCARCITY 50-51 WHAT KATRINA TOOK AWAY 58-59 by the Space Shuttle on September 1, 1985, allowed meteorologists to LOST IN THE FOG 44-45 LETHAL FORCE 52-53 FORESIGHT TO PREVENT TRAGEDIES 60-61 Phenomena evaluate its scope before it reached the BRIEF FLASH 46-47 DEATH AND DESTRUCTION 54-55 Gulf of Mexico. ropical cyclones (called They uproot trees, damage buildings, the government authorities organize require detailed information from the heart hurricanes, typhoons, or cyclones devastate land under cultivation, and preparedness exercises so that the of the storm. The use of artificial satellites in different parts of the world) cause deaths. The Gulf of Mexico is one population knows what to do. To that send clear pictures has contributed cause serious problems and often of the areas of the planet continually understand how hurricanes function greatly to detecting and tracking strong Tdestroy everything in their path. affected by hurricanes. For this reason, and improve forecasts, investigators winds, preventing many disasters. PDF电子书基地 http://dayo1982.400gb.com
38 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 39 Capricious Forms T R O P O S P H E R E The Inside 1.2 to 5 The altitude at which clouds are formed depends on the stability of miles (2-8 km) louds are masses of large drops of water and ice the air and the humidity. The highest and Thickness of a storm cloud crystals. They form because the water vapor -67° F CIRRUS coldest clouds have ice crystals. The lowest and warmest clouds have drops of water. A high, thin cloud with white, C contained in the air condenses or freezes as it rises 6 miles (-55° C) delicate filaments composed classes of clouds depending on their height 150,000 (10 km) There are also mixed clouds. There are 10 through the troposphere. How the clouds develop depends Temperature in of ice crystals above sea level. The highest clouds begin at on the altitude and the velocity of the rising air. Cloud the upper part of a height of 2.5 miles (4 km). The mid-level tons of water the troposphere shapes are divided into three basic types: cirrus, cumulus, CIRROSTRATUS CIRROCUMULUS begins at a height of 1.2 to 2.5 miles (2-4 can be contained in a km) and the lowest at 1.2 miles (2 km) high. storm cloud. and stratus. They are also classified as high, medium, and HIGH CLOUDS A very extensive cloud that A cloud formation eventually covers the whole sky low depending on the altitude they reach above sea level. and has the form of a composed of very small, granulated elements spaced They are of meteorological interest because they transparent, fibrous-looking veil more or less regularly Anvil-shaped top indicate the behavior of the atmosphere. ASCENDING 2.5 miles 14° F CURRENT (4 km) (-10° C) Exosphere TYPES OF CLOUDS The temperature of 300 miles the middle part of NAME MEANING (500 km) the troposphere The CIRRUS FILAMENT ALTOCUMULUS altitude A formation of rounded at which CUMULUS AGGLOMERATION clouds in groups that can it freezes Direction of STRATUS BLANKET form straight or wavy rows the storm Mesosphere NIMBUS RAIN MEDIUM CLOUDS CUMULONIMBUS 50 miles A storm cloud. It portends (90 km) intense precipitation in the Stratosphere Troposphere 30 miles form of rain, hail, or snow. Its Turbulent color is white. winds Troposphere (50 km) ALTOSTRATUS The layer closest to the Earth and in which 6 miles Large, nebulous, compact, uniform, meteorological phenomena occur, including (10 km) slightly layered masses. Altostratus the formation of clouds 0 does not entirely block out the Sun. It is bluish or gray. DESCENDING CURRENT HOW THEY ARE FORMED Clouds are formed when the rising air cools to water vapor condenses. Cumulonimbus clouds CUMULUS the point where it cannot hold the water are storm clouds that can reach a height of A cloud that is generally vapor it contains. In such a circumstance, the 43,000 feet (13,000 m) and contain more dense with well-defined air is said to be saturated, and the excess than 150,000 tons of water. outlines. Cumulus clouds 50° F can resemble a mountain STRATOCUMULUS 1.2 miles (10° C) of cotton. A cloud that is horizontal and very long. It does not blot out the (2 km) Temperature of the Sun and is white or gray in color. lower part of the troposphere Wind Waves NIMBOSTRATUS Nimbostratus portends more or less continuous Convection Convergence Lines of The heat of the Sun warms the air near the When the air coming from one direction precipitation in the form of cumulus ground, and because it is less dense than the meets air from another direction, it is LOW CLOUDS rain or snow that, in most clouds surrounding air, it rises. pushed upward. cases, reaches the ground. STRATUS 59° F A low cloud that extends over (15° C) a large area. It can cause Mild winds Lenticular Rotating cloud cloud drizzle or light snow. Stratus Temperature at the clouds can appear as a gray Earth's surface band along the horizon. SPECIAL FORMATIONS CLOUD STREETS LENTICULAR CLOUDS 0 miles (0 km) The form of the clouds depends on the Mountains usually create waves in the atmosphere on their lee side, and on the winds and the topography of the terrain Geographic elevation Presence of a front 1802 The year that British beneath them. Light winds usually produce crest of each wave lenticular clouds are When the air encounters mountains, it is forced When two masses of air with different meteorologist Luke Howard lines of cumulus clouds positioned as if formed that are held in place by the to rise. This phenomenon explains why there are temperatures meet at a front, the warm air carried out the first along streets. Such waves can be created waves. Rotating clouds are formed by often clouds and rain over mountain peaks. rises and clouds are formed. scientific study of clouds by differences in surface heating. turbulence near the surface. PDF电子书基地 http://dayo1982.400gb.com
38 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 39 Capricious Forms T R O P O S P H E R E The Inside 1.2 to 5 The altitude at which clouds are formed depends on the stability of miles (2-8 km) louds are masses of large drops of water and ice the air and the humidity. The highest and Thickness of a storm cloud crystals. They form because the water vapor -67° F CIRRUS coldest clouds have ice crystals. The lowest and warmest clouds have drops of water. A high, thin cloud with white, C contained in the air condenses or freezes as it rises 6 miles (-55° C) delicate filaments composed classes of clouds depending on their height 150,000 (10 km) There are also mixed clouds. There are 10 through the troposphere. How the clouds develop depends Temperature in of ice crystals above sea level. The highest clouds begin at on the altitude and the velocity of the rising air. Cloud the upper part of a height of 2.5 miles (4 km). The mid-level tons of water the troposphere shapes are divided into three basic types: cirrus, cumulus, CIRROSTRATUS CIRROCUMULUS begins at a height of 1.2 to 2.5 miles (2-4 can be contained in a km) and the lowest at 1.2 miles (2 km) high. storm cloud. and stratus. They are also classified as high, medium, and HIGH CLOUDS A very extensive cloud that A cloud formation eventually covers the whole sky low depending on the altitude they reach above sea level. and has the form of a composed of very small, granulated elements spaced They are of meteorological interest because they transparent, fibrous-looking veil more or less regularly Anvil-shaped top indicate the behavior of the atmosphere. ASCENDING 2.5 miles 14° F CURRENT (4 km) (-10° C) Exosphere TYPES OF CLOUDS The temperature of 300 miles the middle part of NAME MEANING (500 km) the troposphere The CIRRUS FILAMENT ALTOCUMULUS altitude A formation of rounded at which CUMULUS AGGLOMERATION clouds in groups that can it freezes Direction of STRATUS BLANKET form straight or wavy rows the storm Mesosphere NIMBUS RAIN MEDIUM CLOUDS CUMULONIMBUS 50 miles A storm cloud. It portends (90 km) intense precipitation in the Stratosphere Troposphere 30 miles form of rain, hail, or snow. Its Turbulent color is white. winds Troposphere (50 km) ALTOSTRATUS The layer closest to the Earth and in which 6 miles Large, nebulous, compact, uniform, meteorological phenomena occur, including (10 km) slightly layered masses. Altostratus the formation of clouds 0 does not entirely block out the Sun. It is bluish or gray. DESCENDING CURRENT HOW THEY ARE FORMED Clouds are formed when the rising air cools to water vapor condenses. Cumulonimbus clouds CUMULUS the point where it cannot hold the water are storm clouds that can reach a height of A cloud that is generally vapor it contains. In such a circumstance, the 43,000 feet (13,000 m) and contain more dense with well-defined air is said to be saturated, and the excess than 150,000 tons of water. outlines. Cumulus clouds 50° F can resemble a mountain STRATOCUMULUS 1.2 miles (10° C) of cotton. A cloud that is horizontal and very long. It does not blot out the (2 km) Temperature of the Sun and is white or gray in color. lower part of the troposphere Wind Waves NIMBOSTRATUS Nimbostratus portends more or less continuous Convection Convergence Lines of The heat of the Sun warms the air near the When the air coming from one direction precipitation in the form of cumulus ground, and because it is less dense than the meets air from another direction, it is LOW CLOUDS rain or snow that, in most clouds surrounding air, it rises. pushed upward. cases, reaches the ground. STRATUS 59° F A low cloud that extends over (15° C) a large area. It can cause Mild winds Lenticular Rotating cloud cloud drizzle or light snow. Stratus Temperature at the clouds can appear as a gray Earth's surface band along the horizon. SPECIAL FORMATIONS CLOUD STREETS LENTICULAR CLOUDS 0 miles (0 km) The form of the clouds depends on the Mountains usually create waves in the atmosphere on their lee side, and on the winds and the topography of the terrain Geographic elevation Presence of a front 1802 The year that British beneath them. Light winds usually produce crest of each wave lenticular clouds are When the air encounters mountains, it is forced When two masses of air with different meteorologist Luke Howard lines of cumulus clouds positioned as if formed that are held in place by the to rise. This phenomenon explains why there are temperatures meet at a front, the warm air carried out the first along streets. Such waves can be created waves. Rotating clouds are formed by often clouds and rain over mountain peaks. rises and clouds are formed. scientific study of clouds by differences in surface heating. turbulence near the surface. PDF电子书基地 http://dayo1982.400gb.com
40 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 41 The Rain Announces Its Coming 4 RAIN 5 DISSIPATION The descending currents are The upper part of the cloud spreads out like an anvil, and the rain falls stronger than the ascending ones from the lower cloud, producing and interrupt the feeding air, he air inside a cloud is in continuous motion. This process causes the drops of water or the crystals 3 MATURATION descending currents. causing the cloud to disintegrate.. Mature clouds have very strong of ice that constitute the cloud to collide and join together. In the process, the drops and crystals ascending currents, leading to T become too big to be supported by air currents and they fall to the ground as different protuberances and rounded formations. Convection occurs. kinds of precipitation. A drop of rain has a diameter 100 times greater than a droplet in a 6 miles (10 km) cloud. The type of precipitation depends on whether the cloud contains drops of water, ice 4 miles Low, thin clouds (7 km) contain tiny crystals, or both. Depending on the type of cloud and the temperature, the precipitation droplets of water can be liquid water (rain) or solid (snow or hail). -22° F Anvil-shaped and therefore produce rain. (-30° C) When the air cools, it descends and is then heated GROWTH again, repeating the cycle. 2 The smallest clouds adhere to one Coalescence another to form larger clouds, continue to CONDENSATION NUCLEI increasing their size and height. STORM The microdroplets 1 Salt, dust, smoke, and pollen, among other collide and form CLOUD particulates, serve as a surface on which bigger drops. water molecules, ascending by convection, can combine and form water droplets. The air cools. The water 0.02 inch vapor condenses and Heavier drops Dilatation Condensation Collision-Coalescence (0.5 mm) forms microdroplets fall onto a A The molecules B The molecules group C Via this process, of water. lower cloud of water are themselves around molecules collide as fine rain. freeΩwater vapor. a condensation and join together to nucleus. form drops. Water molecules Hydrogen When they begin to fall, the drops have a size of 0.02 inch (0.5 mm), which Oxygen 0.6-1.2 miles 0.2 inch is reduced as they fall (1-2 km) 0.04 inch (5 mm) since they break apart. (1 mm) L EVE L OF CONDENS A T IO N 0.04 inch Sandstorm 68° F 0.07 inch (1 mm) particulates (20° C) (2 mm) Particulates from Volcanic The hot air Forest fire combustion in particulates rises. particulates factories and vehicles 0 miles (0 km) Rock erosion particulates 26,875 trillion Sea-salt particulates molecules occupy 1 cubic millimeter under normal atmospheric conditions. PDF电子书基地 http://dayo1982.400gb.com
40 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 41 The Rain Announces Its Coming 4 RAIN 5 DISSIPATION The descending currents are The upper part of the cloud spreads out like an anvil, and the rain falls stronger than the ascending ones from the lower cloud, producing and interrupt the feeding air, he air inside a cloud is in continuous motion. This process causes the drops of water or the crystals 3 MATURATION descending currents. causing the cloud to disintegrate.. Mature clouds have very strong of ice that constitute the cloud to collide and join together. In the process, the drops and crystals ascending currents, leading to T become too big to be supported by air currents and they fall to the ground as different protuberances and rounded formations. Convection occurs. kinds of precipitation. A drop of rain has a diameter 100 times greater than a droplet in a 6 miles (10 km) cloud. The type of precipitation depends on whether the cloud contains drops of water, ice 4 miles Low, thin clouds (7 km) contain tiny crystals, or both. Depending on the type of cloud and the temperature, the precipitation droplets of water can be liquid water (rain) or solid (snow or hail). -22° F Anvil-shaped and therefore produce rain. (-30° C) When the air cools, it descends and is then heated GROWTH again, repeating the cycle. 2 The smallest clouds adhere to one Coalescence another to form larger clouds, continue to CONDENSATION NUCLEI increasing their size and height. STORM The microdroplets 1 Salt, dust, smoke, and pollen, among other collide and form CLOUD particulates, serve as a surface on which bigger drops. water molecules, ascending by convection, can combine and form water droplets. The air cools. The water 0.02 inch vapor condenses and Heavier drops Dilatation Condensation Collision-Coalescence (0.5 mm) forms microdroplets fall onto a A The molecules B The molecules group C Via this process, of water. lower cloud of water are themselves around molecules collide as fine rain. freeΩwater vapor. a condensation and join together to nucleus. form drops. Water molecules Hydrogen When they begin to fall, the drops have a size of 0.02 inch (0.5 mm), which Oxygen 0.6-1.2 miles 0.2 inch is reduced as they fall (1-2 km) 0.04 inch (5 mm) since they break apart. (1 mm) L EVE L OF CONDENS A T IO N 0.04 inch Sandstorm 68° F 0.07 inch (1 mm) particulates (20° C) (2 mm) Particulates from Volcanic The hot air Forest fire combustion in particulates rises. particulates factories and vehicles 0 miles (0 km) Rock erosion particulates 26,875 trillion Sea-salt particulates molecules occupy 1 cubic millimeter under normal atmospheric conditions. PDF电子书基地 http://dayo1982.400gb.com
42 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 43 SNOW 6 Tiny ice crystals combine to ICE 3 miles VARIED FORMS B 7 HAIL Precipitation in the form of solid Snow crystals can have a variety of shapes; most of CRYSTAL form a hexagonal star, or snowflake. They form at (5 km) them have six points, although some have three or 12, The droplets freeze, and lumps of ice. Hail is produced inside each time they are carried -4° F (-20° C). and they have hexagonal symmetry in a plane. They upward in the cloud, they storm clouds in which frozen -39° F can also be cubic crystals, but these form under acquire a new layer of ice. droplets grow in size as they rise (-39° C) This process, called and fall within the cloud. conditions of extremely low temperature in the highest regions of the troposphere. accretion, increases the HOW CRYSTALS size of the hailstone. A ARE FORMED TYPES OF CRYSTALS Very small hail (0.2 CROSS SECTION OF A HAILSTONE The drop attaches itself to a inch [5 mm] or less nucleus or solid particle. Plate A in diameter) is called snow pellets. Drop SNOWFLAKE 2 miles Vertical air currents Layers Condensation (3 km) Most have cause the of ice six points. nucleus microdroplets to ascend and descend -9° F Column within the cloud. Then the surface of B (-23° C) the drop freezes. The ice Nucleus crystals combine and Dendrite The flakes form measure C Periphery snowflakes. between 0.04 Needle clusters and 0.8 inch When the hailstones C 0.6 mile (1 and 20 mm). are too heavy to be supported by the (1 km) No two snowflakes are If the drops identical to each other. ascending air 0.2 to 2 inches crystallize near 19° F currents, they fall to (5 to 50 mm) the freezing (-7° C) the ground. The typical range of level, they fall hailstone sizes in the form of sleet. A cloud with a greenish WARM tinge or rain with a 2 pounds ASCENDING whitish color can CURRENT The heaviest ASCENDING portend a (1 kg) hailstones WARM hailstorm. CURRENT SLEET that fell on April 14, 1986, in SNOWFALL Gopalganj, Bangladesh. Most snowflakes disintegrate before they reach the ground. They fall as snowflakes only when the air near the ground is very cold. 10 feet (3.11 m) The record of annual snowfall Mount Rainier, Washington. From February 19, 1971, to February 18, 1972. 27° F (-3° C) Temperature of the air FROST HOAR FROST Frost forms when the Similar to frost but 32° F (0° C) dew point of the air is thicker. It usually DEW less than 32° F (0° C), forms when there HYDROMETEORS Water vapor that condenses DEW POINT and the water vapor is fog. during the night into very small Drops of condensed or frozen water drops. The condensation forms 41° F (5° C) transforms directly into ice when it is deposited in the atmosphere are called on surfaces that radiate heat on surfaces. hydrometeors. These include rain, during the night, such as plants, Temperature of the ground fog, hail, mist, snow, and frost. animals, and buildings. PDF电子书基地 http://dayo1982.400gb.com
42 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 43 SNOW 6 Tiny ice crystals combine to ICE 3 miles VARIED FORMS B 7 HAIL Precipitation in the form of solid Snow crystals can have a variety of shapes; most of CRYSTAL form a hexagonal star, or snowflake. They form at (5 km) them have six points, although some have three or 12, The droplets freeze, and lumps of ice. Hail is produced inside each time they are carried -4° F (-20° C). and they have hexagonal symmetry in a plane. They upward in the cloud, they storm clouds in which frozen -39° F can also be cubic crystals, but these form under acquire a new layer of ice. droplets grow in size as they rise (-39° C) This process, called and fall within the cloud. conditions of extremely low temperature in the highest regions of the troposphere. accretion, increases the HOW CRYSTALS size of the hailstone. A ARE FORMED TYPES OF CRYSTALS Very small hail (0.2 CROSS SECTION OF A HAILSTONE The drop attaches itself to a inch [5 mm] or less nucleus or solid particle. Plate A in diameter) is called snow pellets. Drop SNOWFLAKE 2 miles Vertical air currents Layers Condensation (3 km) Most have cause the of ice six points. nucleus microdroplets to ascend and descend -9° F Column within the cloud. Then the surface of B (-23° C) the drop freezes. The ice Nucleus crystals combine and Dendrite The flakes form measure C Periphery snowflakes. between 0.04 Needle clusters and 0.8 inch When the hailstones C 0.6 mile (1 and 20 mm). are too heavy to be supported by the (1 km) No two snowflakes are If the drops identical to each other. ascending air 0.2 to 2 inches crystallize near 19° F currents, they fall to (5 to 50 mm) the freezing (-7° C) the ground. The typical range of level, they fall hailstone sizes in the form of sleet. A cloud with a greenish WARM tinge or rain with a 2 pounds ASCENDING whitish color can CURRENT The heaviest ASCENDING portend a (1 kg) hailstones WARM hailstorm. CURRENT SLEET that fell on April 14, 1986, in SNOWFALL Gopalganj, Bangladesh. Most snowflakes disintegrate before they reach the ground. They fall as snowflakes only when the air near the ground is very cold. 10 feet (3.11 m) The record of annual snowfall Mount Rainier, Washington. From February 19, 1971, to February 18, 1972. 27° F (-3° C) Temperature of the air FROST HOAR FROST Frost forms when the Similar to frost but 32° F (0° C) dew point of the air is thicker. It usually DEW less than 32° F (0° C), forms when there HYDROMETEORS Water vapor that condenses DEW POINT and the water vapor is fog. during the night into very small Drops of condensed or frozen water drops. The condensation forms 41° F (5° C) transforms directly into ice when it is deposited in the atmosphere are called on surfaces that radiate heat on surfaces. hydrometeors. These include rain, during the night, such as plants, Temperature of the ground fog, hail, mist, snow, and frost. animals, and buildings. PDF电子书基地 http://dayo1982.400gb.com
44 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 45 Lost in the Fog Types of Fog Radiation fog forms during cold nights These fogs are thick and persistent. Advection when the land loses the heat that was evaporate, and the air tends to become saturated. FRONTAL FOG hen atmospheric water vapor condenses near the ground, it forms fog and mist. The absorbed during the day. Frontal fog forms when fog occurs when humid, warm air flows over a 2. Formed ahead of a warm front fog consists of small droplets of water mixed with smoke and dust particles. Physically water that is falling has a higher temperature surface so cold that it causes the water vapor than the surrounding air; the drops of rain from the air to condense. W the fog is a cloud, but the difference between the two lies in their formation. A cloud develops when the air rises and cools, whereas fog forms when the air is in contact with the ground, which cools it and condenses the water vapor. The atmospheric phenomenon of 1. RADIATION FOG This fog appears only on the ground fog decreases visibility to distances of less than 1 mile (1.6 km) and can affect and is caused by radiation cooling of the Earth's surface. ground, maritime, and air traffic. When the fog is light, it is called mist. In this case, visibility is reduced to 2 miles (3.2 km). FO G FO G Orographic barrier ADVECTION FOG Fog develops on lee-side mountain 3. Formed when a mass of humid slopes at high altitudes and occurs and cool air moves over a surface that is colder than the air when the air becomes saturated with moisture. FO G 160 feet (50 m) 4. The densest fog affects visibility at this distance and has repercussions on car, boat, and OROGRAPHIC airplane traffic. In many cases, FOG visibility can be zero. The air becomes saturated as it ascends. Dew The condensation of water ASCENDING Warm air vapor on objects that have AIR Fog and Visibility radiated enough heat to BL O C K E D decrease their temperature FO G Visibility is defined as a measure of an observer's below the dew point ability to recognize objects at a distance through the atmosphere. It is expressed in miles and indicates the visual High Wind limit imposed by the presence of fog, mist, dust, smoke, or landmasses any type of artificial or natural precipitation in the atmosphere. The different degrees of fog density have Mist various effects on maritime, land, and air traffic. Mist consists of salt and other dry particles imperceptible to the naked eye. When the concentration of these particles is very high, the clarity, color, texture, and form of objects we see are diminished. INVERSION FOG When a current of warm, humid air flows over the cold water of an ocean or DENSE THICK FOG MIST lake, an inversion fog can form. The FOG FOG warm air is cooled by the water, and its moisture condenses into droplets. The Means of transport warm air traps the cooled air below it, are affected 6 miles near the surface. High coastal by visibility. landmasses prevent this type of fog (10 km) 0.6 mile 1.2 miles 1.9 miles from penetrating very far inland. (1 km) (2 km) (3 km) Normal visibility 160 feet 660 feet (50 m) (200 m) PDF电子书基地 http://dayo1982.400gb.com
44 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 45 Lost in the Fog Types of Fog Radiation fog forms during cold nights These fogs are thick and persistent. Advection when the land loses the heat that was evaporate, and the air tends to become saturated. FRONTAL FOG hen atmospheric water vapor condenses near the ground, it forms fog and mist. The absorbed during the day. Frontal fog forms when fog occurs when humid, warm air flows over a 2. Formed ahead of a warm front fog consists of small droplets of water mixed with smoke and dust particles. Physically water that is falling has a higher temperature surface so cold that it causes the water vapor than the surrounding air; the drops of rain from the air to condense. W the fog is a cloud, but the difference between the two lies in their formation. A cloud develops when the air rises and cools, whereas fog forms when the air is in contact with the ground, which cools it and condenses the water vapor. The atmospheric phenomenon of 1. RADIATION FOG This fog appears only on the ground fog decreases visibility to distances of less than 1 mile (1.6 km) and can affect and is caused by radiation cooling of the Earth's surface. ground, maritime, and air traffic. When the fog is light, it is called mist. In this case, visibility is reduced to 2 miles (3.2 km). FO G FO G Orographic barrier ADVECTION FOG Fog develops on lee-side mountain 3. Formed when a mass of humid slopes at high altitudes and occurs and cool air moves over a surface that is colder than the air when the air becomes saturated with moisture. FO G 160 feet (50 m) 4. The densest fog affects visibility at this distance and has repercussions on car, boat, and OROGRAPHIC airplane traffic. In many cases, FOG visibility can be zero. The air becomes saturated as it ascends. Dew The condensation of water ASCENDING Warm air vapor on objects that have AIR Fog and Visibility radiated enough heat to BL O C K E D decrease their temperature FO G Visibility is defined as a measure of an observer's below the dew point ability to recognize objects at a distance through the atmosphere. It is expressed in miles and indicates the visual High Wind limit imposed by the presence of fog, mist, dust, smoke, or landmasses any type of artificial or natural precipitation in the atmosphere. The different degrees of fog density have Mist various effects on maritime, land, and air traffic. Mist consists of salt and other dry particles imperceptible to the naked eye. When the concentration of these particles is very high, the clarity, color, texture, and form of objects we see are diminished. INVERSION FOG When a current of warm, humid air flows over the cold water of an ocean or DENSE THICK FOG MIST lake, an inversion fog can form. The FOG FOG warm air is cooled by the water, and its moisture condenses into droplets. The Means of transport warm air traps the cooled air below it, are affected 6 miles near the surface. High coastal by visibility. landmasses prevent this type of fog (10 km) 0.6 mile 1.2 miles 1.9 miles from penetrating very far inland. (1 km) (2 km) (3 km) Normal visibility 160 feet 660 feet (50 m) (200 m) PDF电子书基地 http://dayo1982.400gb.com
Edited by Foxit PDF Editor Copyright (c) by Foxit Software Company, 2004 For Evaluation Only. 47 produced by the air when 3rd phase 3rd return This discharge, as in the second stroke, branches. When the ceases, the lightning flash sequence comes WEATHER AND CLIMATE THUNDER This is the sound it expands very rapidly, generating shock waves as it is heated. DISCHARGE The discharge takes place from the cloud toward the ground after the stepped leader, a channel of ionized air, extends down to the ground. Lightning bolt: 8,700 miles per second (140,000 km/s) 110 volts is consumed by a lamp. 2nd phase 2nd return C does not have return discharge to an end. Very hot Cold air air 4. miles per second (140,000 km/s) speed Airplane: 0.2 mile per second (0.3 km/s) F1 car: 0.06 mile per second (0.1 km/s) 100 million volts IS THE ELECTRICAL POTENTIAL OF A LIGHTNING BOLT. generates 200 RETURN STROKE In the final phase, the discharge rises from the Earth to the cloud. 1st phase 1st return B If the cloud has additional electrical charges, they are propagated to the ground through the channel of the first stroke and generate a second return stroke toward the cloud. Very hot air 8,700 A windmill volts. 5. DISCHARGE SEQUENCE channel The lightning bolt propagates through an ionized channel that branches out to reach the ground. Electrical charges run along the same channel in the opposite direction. Cold air The cloud's negative charges are attracted to the positive charges of the ground. The difference in electrical potential between the two regions produces the discharge. A ELECTRICAL CHARGES INDUCED CHARGE The negative charge of the base of the cloud induces a positive charge in the ground below it. lectrical storms are produced in large cumulonimbus-type clouds, which typically cloud and the air, or between one cloud and another. This is how the flash of lightning bring heavy rains in addition to lightning and thunder. The storms form in areas then discharged with a zigzag flash between the cloud and the ground, between the is unleashed. Moreover, the heat that is released during the discharge generates an atmosphere. Inside the cloud, an enormous electrical charge accumulates, which is of low pressure, where the air is warm and less dense than the surrounding 3. POINT OF IMPACT 65 feet (20 m) This is the radius of a lightning bolt's effective range on the surface of the Earth. PDF电子书基地 http://dayo1982.400gb.com expansion and contraction of the air that is called thunder. INSIDE THE CLOUD Electrical charges are produced from the collisions between ice or hail crystals. Warm air currents rise, causing the charges in the cloud to shift. SEPARATION The charges become separated, with the positive charges accumulating at the top of the cloud and the negative charges at the base. 2. Cloud-to-ground Negative charges of the cloud are attracted by the positive charges of the ground. A lightning rod is an instrument whose purpose is to attract a lightning bolt and channel the electrical discharge to the ground so discharge. That marked the birth of the lightning rod, which consists of an iron rod placed on the highest point of the object to be protected and connected to the ground by a metallic, insulated conductor. The principle of all lightning rods, which terminate in one or more points, is to attract METEOROLOGICAL PHENOMENA Brief Flash Warm air ORIGIN Lightning originates within large cumulonimbus storm clouds. Lightning bolts can have negative or positive electric charges. TYPES OF LIGHTNING Lightning can be distinguished primarily by the path taken by the electrical charges that Cloud-to-cloud A lightning flash can occur within a cloud or between two oppositely charged areas. LIGHTNING RODS The primary function of lightning rods is to facilitate the electrostatic discharge, which follows the path of least electrical resistance. Tip of the conductor Lightning that it does no harm to buildings or people. A famous experiment by Benjamin Franklin led to the invention of this apparatus. During a lightning storm, he flew a kite into clouds, and it received a strong and conduct the lightning bolt to the ground. 46 E Cold air 1. cause them. Cloud-to-air The electricity moves from the cloud toward an air mass of opposite charge. rod
48 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 49 When Water Accumulates Torrential Torrential Snow increases runoff rains Rains raise the level of into the rivers. ater is a vital element for life, but in excess it leads to serious consequences for people Caused by low pressure the water in the rivers and the systems, instability of and their economic activity. Flooding occurs when certain areas that are normally dry the air mass, and high riverbeds. W are covered with water for a more or less prolonged period. The most important causes humidity are excessive rains, the overflow of rivers and lakes, and giant waves that wash over the coast. Such waves can be the result of unusually high tides caused by strong surface winds or by submarine earthquakes. Walls, dikes, dams, and embankments are used to help prevent flooding. Little or no rain penetrates into the valley slopes covered with pines. Principal Tributary Flooded Land Floodplains river river Plants with thick, Floodplains are areas adjacent When land is flooded for days or droopy stems to rivers or streams that are months, the air in the soil is replaced by water, which prevents the buildup of subject to recurrent flooding. oxygen, thus affecting the biological activity of plants and the soil itself. In the latter Low-lying terrain case, if the water does not have sufficient The main river cannot salt, the incomplete decomposition of organic contain the increased matter and the significant washing away of There is so much flow of the tributary nutrients make the soil more acidic. If the water on the rivers. surface that the soil water contains a great deal of salt, the salt cannot absorb it. will remain in the soil, causing a different problem: salinization. The soil cannot carry oxygen to the roots. 250,000 Solid particulates Victims of flooding in the Bay Reduction The water Large rivers cross the Houses and of Bengal, Bangladesh, in 1970 trees covered causes a decline The components of the soil that in oxygen in the plains, which suffer with water are oxidized can be reduced and aerated spaces of from regular flooding thus change their properties. the soil. Dam Filtering grates Natural Transformers stores water to prevent the passage of Hydroelectric Flood Control dam course of Their job is to divert it or to unwanted objects in the With the construction of dikes and the river transform the voltage regulate its flow water used to produce hydroelectric power. outside the riverbed. of the electric current. embankments, the flow of rivers prone to flooding is largely contained. Agriculture is more productive when water can be controlled. Channeling water via turbines also generates Electrical electricity. energy can be made available to houses. Hydroelectric Plants Elevation EMBANKMENT use the force and velocity of running of the reservoir Earthen embankments help water to turn turbines. There are two contain rivers that tend to STORM types: run-off-river (which uses the Electrical generator overflow and temporarily DIKES natural kinetic energy of the river's Equipment that change course. In areas where the coast running waters) and reservoir (where the produces electricity by is low and exposed to flooding, water accumulates behind dams and is Electrical converting the protective dikes have been constructed then released under increased pressure to power lines mechanical energy of against high tides and powerful waves. the power plant). the rotating turbine into electrical energy PDF电子书基地 http://dayo1982.400gb.com
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