Why is the summer monsoon in South Asia stronger than the winter monsoon?

The reason why the summer monsoon in South Asia is stronger than the winter monsoon is mainly the difference of thermal properties between land and sea and the pressure gradient force.

In winter, cold high pressure forms in Mongolia and Siberia, resulting in horizontal pressure gradient force from south to north. At the same time, the subtropical high in the southern hemisphere is weak and cannot form a strong pressure gradient. In summer, the equatorial depression moves to the southern hemisphere, and the subtropical high in the southern hemisphere moves relatively northward. The horizontal pressure gradient force formed by them moves from north to south, and the high temperature and high humidity in South Asia form a strong summer monsoon.