Dear Student,
The arrival of monsoon is called the onset of monsoon. It sets in early June and stays till mid-September.
Following factors are responsible for monsoon in India:
* 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 Dear Studentmalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer.