Monsoon is derived from the arabic world Mausum meaning the seasonal reversal of winds. Various factors responsible for the origin of Indian Monsoon are as follows:-
- Under the extreme low pressure condition on land, the wind from the southern part of the Indian Ocean (south of Equator) is attracted towards the subcontinent of India.
- The air corning from oceans towards land is warm and moist.
- When land barriers like mountain ranges and plateaus come in the way of the moisture-laden winds, they ascend and result into saturation, condensation, and precipitation
- the Northern Hemisphere during winter season, there develops high pressure areas near Baikal Lake (Siberia), and Peshawar {Pakistan).
- the Indian Ocean and the Pacific Ocean {south of Japan) remain relatively warm, having low pressure areas.
- There is an outflow of air from the high pressure of the land to the low pressure areas of the oceans.
- The air blowing from high pressure areas of land towards the sea is cold and dry.
- This cold and dry air is incapable of giving precipitation unless it comes into contact with some water body (ocean/sea)
- Besides differential heating, the origin and development of monsoon are also influenced by the shape of the continents, orography, and the conditions of air circulation in the upper troposphere.
- Development of equatorial westerly because of inter tropical convergence.
- Role of Tropical easterly jet stream and westerly jet stream in onset and withdrawal of monsoon.
- El Nino and La Nina effect