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PRESENTS THE KEY TO UPSC MAINS 2019 PAPER 1 Copyright © Aspire IAS All rights are reserved. No part of this document may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior permission of Aspire IAS.

INDEX

PAST YEAR QUESTIONS Explain the factors responsible for the origin of ocean currents. How do they influence regional climates, fishing and navigation? How far do you agree that the behavior of the Indian monsoon has been changing due to humanizing landscapes? Discuss. Mumbai, Delhi and Kolkata are the three mega cities of the country but the air pollution is much more serious problem in Delhi as compared to the other two. Why is this so? India is well endowed with fresh water resources. Critically examine why it still suffers from water scarcity. The states of Jammu and Kashmir, Himachal Pradesh and Uttarakhand are reaching the limits of their ecological carrying capacity due to tourism. Critically evaluate. Smart cities in India cannot sustain without smart villages. Discuss this statement in the backdrop of rural urban integration. What are the economic significances of discovery of oil in Arctic Sea and its possible environmental consequences?' Most of the unusual climatic happenings are explained as an outcome of the EI-Nino effect. Do you agree? Why are the world's fold mountain systems located along the margins of continents? Bring out the association between the global distribution of fold mountains and the earthquakes and volcanoes. Explain the formation of thousands of islands in Indonesian and Philippines archipelagos. Tropical cyclones are largely confined to South China Sea, Bay of Bengal and Gulf of Mexico. Why? Critically evaluate the various resources of the oceans which can be harnessed to meet the resource crisis in the world. Bring out the relationship between the shrinking Himalayan glaciers and the symptoms of climate change in the Indian sub-continent.

Whereas the British planters had developed tea gardens all along the Shivaliks and Lesser Himalayas from Assam to Himachal Pradesh, in effect they did not succeed beyond the Darjeeling area. Explain. Why did the Green Revolution in India virtually by-pass the eastern region despite fertile soil and good availability of water? How does India see its place in the economic space of rising natural resource rich Africa? What do you understand by the theory of 'continental drift'? Discuss the prominent evidences in its support. The recent cyclone on east coast of India was called 'Phailin'. How are the tropical cyclones named across the world? Elaborate. Bring out the causes for the formation of heat islands in the urban habitat of the world. What do you understand by the phenomenon of 'temperature inversion' in meteorology? How does it affect weather and the habitants of the place? Major hot deserts in northern hemisphere are located between 20-30 deg N latitudes and on the western side of the continents. Why? Bring out the causes for more frequent occurrence of landslides in the Himalayas than in the Western Ghats. There is no formation of deltas by rivers of the Western Ghats. Why? Do you agree that there is a growing trend of opening new sugar mills in southern States of India? Discuss with justification. With growing scarcity of fossil fuels, the atomic energy is gaining more and more significance in India. Discuss the availability of raw material required for \"the generation of atomic energy in India and in the world. GUESS PAPER - TOPICS EXPECTED TO BE ASKED IN THIS YEAR’S EXAM, BASED ON CONTEMPORARY ISSUES AND PAST YEARS’ PATTERN, HAVE BEEN COVERED IN DETAIL.

PHYSICAL GEOGRAPHY

CLIMATOLOGY ATMOSPHERE AND TEMPERATURE DISTRIBUTION FIGURE: VERTICAL TEMPERATURE DISTRIBUTION AND LAYERS OF ATMOSPHERE

Earth intercepts only one in two billion parts of solar radiation. This intercepted radiation is called Insolation. Earth receives Sun’s radiation (heat) in the form of short waves which are of electromagnetic nature. The earth absorbs short wave radiation during daytime and reflects back the heat received into space as long-wave radiation during night. Through this give and take, or the heat budget, the earth maintains a constant temperature. The heat energy from the solar radiation is received by the earth through three mechanisms—  Radiation: Heat transfer from one body to another without actual contact or movement. It is possible in relatively emptier space, for instance, from the sun to the earth through space.  Conduction: Heat transfer through matter by molecular activity. Heat transfer in iron and other metals is by conduction. Generally, denser materials like water are good conductors and a lighter medium like air is a bad conductor of heat.  Convection: Transfer of heat energy by actual transfer of matter or substance from one place to another. FACTORS AFFECTING TEMPERATURE DISTRIBUTION  Duration of sunshine and seasons.  Transparency of atmosphere.  Land-sea differential albedo.  Prevailing winds and ocean currents.  Slope aspects and altitude.  Vegetation and soil. FIGURE: HORIZONTAL DISTRIBUTION OF TEMPERATURE

SEASONAL DISTRIBUTION OF TEMPERATURE

PREVAILING WINDS AND PRESSURE SYSTEMS Wind is the horizontal movement of air. Currents are vertical movement of air. Winds balance uneven distribution of pressure globally. They help in transfer of heat, moisture etc. from one place to another. The pattern of planetary winds depends on:  latitudinal variation of atmospheric heating  emergence of pressure belts and pressure gradient force  the migration of belts following apparent path of the sun  the distribution of continents and oceans  the rotation of earth and coriolis force  frictional force exerted by different physiography like mountains etc. The pattern of the movement of the planetary winds is called the general circulation of the atmosphere. The general circulation of the atmosphere also sets in motion the ocean water circulation which influences the earth’s climate. Differences in atmospheric pressure generate winds. At the Equator, the sun warms the water and land more than it does the rest of the globe. Warm equatorial air rises higher into the atmosphere and migrates toward the poles. This is a low-pressure system. At the same time, cooler, denser air moves over Earth’s surface toward the Equator to replace the heated air. This is a high-pressure system. Winds generally blow from high-pressure areas to low-pressure areas. The boundary between these two areas is called a front. The complex relationships between fronts cause different types of wind and weather patterns. Prevailing winds are winds that blow from a single direction over a specific area of the Earth. Areas where prevailing winds meet are called convergence zones. Generally, prevailing winds blow east- west rather than north-south. This happens because Earth’s rotation generates what is known as the Coriolis effect. The Coriolis effect makes wind systems twist counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.



SECONDARY WINDS These winds change their direction with change in season. Monsoons are the best example of large-scale modification of the planetary wind system. Other examples of periodic winds include cyclones and anticyclones, jet stream and air masses. These winds are primarily the result of unequal distribution of land and water, and the resultant difference in pressure, on a local level. It is the product of Adiabatic Lapse Rate and Diabatic Lapse Rate, and resultant changes in stability. They greatly impact the economy and culture of a place. Monsoon winds also help in reducing the pollution. MONSOON  Monsoons were traditionally explained as land and sea breezes on a large scale. Thus, they were considered a convectional circulation on a giant scale. The monsoons are characterized by seasonal reversal of wind direction.  During summer, the trade winds of southern hemisphere are pulled northwards by an apparent northward movement of the sun and by an intense low pressure core in the north-west of the Indian subcontinent. While crossing the equator, these winds get deflected to their right under the effect of Coriolis force.

 These winds now approach the Asian landmass as south-west monsoons. Since they travel a long distance over a vast expanse of water, by the time they reach the south-western coast of India, they are over-saturated with moisture and cause heavy rainfall in India and neighbouring countries.  During winter, these conditions are reversed and a high pressure core is created to the north of the Indian subcontinent. Divergent winds are produced by this anticyclonic movement which travels southwards towards the equator. This movement is enhanced by the apparent southward movement of the sun. These are north-east or winter monsoons which are responsible for some precipitation along the east coast of India.  Outside India, in the eastern Asiatic countries, such as Australia, China and Japan, the winter monsoon is stronger than the summer monsoon. (we will study about monsoons in detail while studying Indian Climate)

JET STREAMS Jet streams are the strong air streams present in the upper troposphere, lower stratosphere, and possibly even mesosphere which help to complete the global circulation and characterised by strong vertical and lateral wind shear. They are relatively narrow belts of swift-moving winds having velocity in the range of 100km/hr to 900km/hr.  The temperature gradient from the equator towards the poles, the surface high pressure at the poles and genesis of the circumpolar whirl above the poles caused by tropospheric low pressure are the major causes of the origin of the Jet Streams.  Due to the subsidence of the cool air over the Arctic region, the surface high pressure is intensified while upper air low pressure develops in the upper troposphere.  Because of this phenomenon a cyclonic system of air circulation, whose direction is from west to east in the form of whirl develops around upper tropospheric low pressure and the equatorward meandering part of this upper air circulation is called Jet Stream. Types of Jet Streams SUB-  The sub-tropical jet stream is produced by the earth’s rotation (Coriolis force) TROPICAL and temperature contrast between tropical and sub – tropical regions. WESTERLY JET  At the equator, the rotation produces greatest velocity in the atmosphere. As a STREAM result, the rising air which spreads out northwards and southwards, moves faster than the latitudes over which it is blowing.  It is deflected to the right in the northern hemisphere and to the left in the southern hemisphere, and at about 30° latitude, it becomes concentrated as the subtropical jet streams.  They originate at the meeting point of Hadley and Ferrel Cell. The immense temperature contrast between two air masses produce a sudden change in the pressure gradient, thus sudden change in the velocity.  On account of permanency of the Hadley cell, this Jetstream remains intense throughout the year although, with the shifting of the pressure belt, its path also shifts North-South.  It is closely connected to the Indian and African summer monsoons. It has a major role in bringing western disturbances to India during the winter season and thus provides crucial rainfall which is vital for Rabi Crop.

TROPICAL  There are also major high velocity winds in the lower troposphere called low- EASTERLY level jets. In the tropics, the most prominent of these are the Somali Jet and JET the African Easterly Jet. STREAM  The Tropical Easterly Jetstream is a unique and dominant feature of the northern hemispheric summer over southern Asia and northern Africa. It is found near between 5° and 20°N.  It is fairly persistent in its position, direction, and intensity from June through the beginning of October.  Its establishment and maintenance is not fully understood but it is believed that the jet may be caused by the uniquely high temperatures and heights over the Tibetan Plateau during summer, due to which low pressure (converging) sets up at the surface and relatively higher pressure(diverging) in the upper troposphere. The part of this southward diverging air comes under the impact of Coriolis Effect and it is forced to deflect from east to west leading to the formation of a tropical Jetstream.  It has a relationship with oscillation and shifting of ITCZ (Inter-Tropical Convergence Zone) and Monsoon Trough.  During the onset of winter, it suddenly disappears while its arrival heralds the onset of the South West Monsoon.

POLAR  The polar front jet is produced by a temperature difference and is closely related NIGHT JET to the polar front. STREAM  It has a more variable position than the sub-tropical jet. In summer, its position shifts towards the poles and in winter towards the equator.  The jet is strong and continuous in winter.  It greatly influences climates of regions lying close to 60 degree latitude.  It determines the path and speed and intensity of temperate cyclones.  Polar Night Jet Stream help in increasing the intensity of Polar Anticyclone.  They are called polar nights as jet streams are formed in winter nights of 6 months at poles. It is found due to the thermal contrast between sub-polar layers and polar layers, and become westerly due to Coriolis force.  This jet has been found in the stratosphere little below the maximum concentration of ozone thus also known as Stratospheric Jet Stream.