What are the main factors that control monsoon in India?

Question

What are the main factors that control monsoon in India?

Answer 1

During the south-west monsoon season in India,a wedge type trough of low pressure extending from west to east in the Northern India developes and the axis of the trough lies approximately along New Delhi and  Calcutta.This trough oscillates from its mean position.If it moves towards south,the monsoon becomes vigourous and its northward movement towards the foot of the Himalayas weakens the monsoon.

The low pressure area which usually  forms over the Siberia during this period intensifies, the monsoon also becomes strong over India.

Answer 2

The heating of the continent relative to the heating of the Indian Ocean.  When the continent is warm the pressure is low relative to the ocean and the monsoon blows from the ocean to the land, bringing heavy rain with it.  During the winter the Himalayan Plateau is cold relative to the ocean, forming high pressure over land and causing a dry monsoon to blow from land to sea.

There are complicating factors such as the "Madden-Julian" oscillation, but it is the differential heating of ocean and land that is the biggest control