Explain the three factors which affect the mechanism of monsoon .

Dear Student,

Three factors that impact mechanism of monsoon  are:

a. Shifting of ITCZ-Inter Tropical Convergence Zone (ITCZ)  which is the equatorial trough (lower pressure area impacts India's climate to a great extent. It is an area where north East and south east trade winds come together and impacts the rainfall .Shifting of ITCZ results in advancing and retreating monsoon in the country.  In advancing monsoon, the trough and its axis keeps on moving northward or southward, which determines the spatial distribution of rainfall, for example, When the axis of the monsoon trough lies over
the plains, rainfall is good in these parts.While for retreating monsoon,with the movement of the sun towards the south, the monsoon trough becomes weaker and we experience withdrawal of monsoon.   When ITCZ and jet streams move southwards towards tropic of Capricorn it leads to dry monsoon in India

b. Different pressure condition-   During advancing monsoon low pressure conditions develops over northern plains and during retreating , high pressure system develops that weakens the south west monsoon. Such different pressure conditions , impacts the monsoon in our country.

c. Effect of EL Nino: EL Nino is the event where the waters of the tropical central and Eastern pacific become warmer than normal. This has the effect of increasing rainfall in this general area, but over the Western Pacific air pressures tend to increase and suppress rainfall thus it is typically drier than average in that region. El Nino in India makes Monsoon weak, and kills it.  El Nino weakens the trade winds, may even lead to reverse wind direction that allows the warmer water from the western Pacific to flow towards the east.  Shift of warm waters from eastern south Indian ocean may impact the rainfall in South east Asia. 


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To understand the mechanism of the monsoons, the following facts are important. The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure. The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator – also known as the monsoon trough during the monsoon season). The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean. The intensity and position of this high-pressure area affects the Indian Monsoon. The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of high pressure over the plateau at about 9 km above sea level. The movement of the westerly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer.
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