Explain the mechanism of monsoon in India.
The monsoons strangely affect the climate of India. To understand the mechanism of the Indian monsoon, it is first important to understand the few facts. These are
i. Differences in heating and cooling of land and sea (land gets heated rapidly and sea takes time in absorbing and releasing heat) creates low pressure area on land and high pressure area over the sea.
ii. The shift of ITCZ zone over the Ganga Plains during summers
iii. The presence of high pressure area to the east of Madagascar
iv. Intense heating of the Tibetan Plateau
v. Movement of jet streams
Due to the high pressure areas over the seas, the warm winds blowing over the Indian Ocean pick up enough moisture and strike the Indian sub-continent in the first week of June.
The monsoon winds then get divided into two branches- the Arabian Sea branch and the Bay of Bengal branch. While the rains of the Arabian Sea branch reache Mumbai by the last week of June, the rains of Bay of Bengal rapidly approach the north eastern part of the country by the first week of June. The rainfall in India is largely affected by the relief features. For example, the places lying in the windward side of the mountains get adequate rainfall while those lying in the leeward side get scanty rainfall. By the first week of July, rainfall reaches the northern parts of the country.
The monsoon begins to retreat by early September from the north western parts of the country. By early December, monsoon completely retreats from the entire country.