Page 1 : crosses the equator, and turns right towards the low-pressure areas over the Indian subcontinent. These, , are known as the Southwest Monsoon winds., , * These winds blow over the warm oceans, gather moisture and bring widespread rainfall over the, , mainland of India., , upper air circulation in this region is dominated by a westerly flow. An important component of this, , —, , “YD EQ ~ J, , ‘ams are located approximately over 27°-30° north latitude, therefore, they are known as, , tropical westerly jet streams. Over India, these jet streams blow south of the Himalayas, all through, , Be, , he year except in summer., , + “The western cyclonic disturbances experienced in the north and north-western parts of the country are, , ~ brought in by this westerly flow. In summer, the subtropical westerly jet stream moves north of the, Himalayas with the apparent movement of the sun. An easterly jet stream, called the sub-tropical, easterly jet stream blows over peninsular India, approximately over 14°N during the summer months., , Coriolis force: An apparent force caused by the earth's,, rotation. The Coriolis force is responsible for deflecting, winds towards the right in the northern hemisphere, and towards the left in the southern hemisphere. This, is also known as ‘Ferrel’s Law’., , Jet stream: These are a narrow belt of high, , altitude (above 12,000 m) westerly winds in the, , troposphere. Their speed varies from about 110, , km/h in summer to about 184 km/h in winter., , ‘A number of separate jet streams have been, , jentified. The most constant are the mid-latitude, the sub-tropical jet stream., , 7, ZF ”, , Western Cyclonic Disturbances, , ‘The western cyclonic disturbances are weather, phenomena of the winter months brought in by the, ‘westerly flow from the Mediterranean region. They, usually influence the weather of the north and, north-western regions of India. Tropical cyclones, occur during the monsoon, as well as, in, ‘October — November, and are part of the easterly, flow. These disturbances affect the coastal regions, of the country. Have you read or heard about the, disasters caused by them on Odisha and Andhra, Pradesh coast?, , WY, , INDIAN MONSOON, , + The climate of India is strongly influenced by monsoon winds., , *+ The sailors first noticed the phenomenon of the monsoon. They benefited from the reversal of the wind, system as they came by sailing ships at the mercy of winds. The Arabs, who had also come to India as, traders named this seasonal reversal of the wind system ‘monsoon’., , * Experienced in the tropical area roughly between 20° N and 20°S., , + To understand the mechanism of the monsoons, the follo, , , , 1g facts are important., , 1. The differential heating and cooling of land{Low pressure) and water(high pressure)., 2, The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain,, 3, The presence of the high-pressure area,east of Madagascar, approximately at 20°S over the Indian, , Ocean., , 4, The Tibetan plateau gets intensely heated during summer, which results in strong ver, , , , ‘and the formation of low pressure over the plateau at about 9 km above sea level., 5. The movement of the westerly jet stream fo the north of the Himalayas and the presence of the ~, tropical easterly jet stream over the Indian peninsula during summer., , —, , “YD EQ ~ J