Question

why is summer the season of rainfall in most part of asia

Answer 1

The major cause of rain production is moisture moving along three-dimensional zones of temperature and moisture contrasts known as weather fronts. If enough moisture and upward motion is present, precipitation falls from convectiveclouds (those with strong upward vertical motion) such as cumulonimbus (thunder clouds) which can organize into narrow rainbands. In mountainous areas, heavy precipitation is possible where upslope flowis maximized within windward sides of the terrain at elevation which forces moist air to condense and fall out as rainfall along the sides of mountains.

Answer 2

Due to more evaporation the water goes to cloud and it became heavy and rain occasion.