What is the mechanism of monsoon? Give characters of retreating and arriving monsoons. What are the factors responsible for causing winter rainfall in the northen planis?
Mechanism of Monsoon involves the following concept:
The phenomena of monsoon refer to the seasonal reversal of winds. It is because while the South West Monsoon winds blow from sea to land at the end of the summer season, the North east winds blow from land to sea during the winter season.
During the summer season the Indian mainland gets intensely heated up creating low pressure. High pressure area is created over the Indian Ocean due to the differential heating of the land and the sea. Because the winds blow from high pressure to low pressure areas, the South West Monsoon winds blow from Sea towards the Indian mainland. When moisture laden winds strike the Western Ghats and the mountains of north eastern parts of the country, they shed their moisture causing rainfall on the places lying on the windward side of the mountains. The Monsoon is also aided by the Inter Tropical Convergence Zone or Monsoon trough near the Equator where winds from northern and southern hemisphere merge. During winters, the Indian mainland begins to cool down creating high pressure areas. Thus the north eastern winds blow from land and hence do not cause enough rainfall. They cause rainfall over the Coromandel Coast during winters.