WINDS converge.It is a zone where air tends to ascend.The Inter-Tropical Convergence Zone located around 20°N-25°N latitudes (over the Gangetic plain) in July month is sometimes called the monsoon trough.This monsoon trough leads to the formation of thermal low over north and northwest regions in India. The trade winds of the southern hemisphere CROSS the equator between 40° and 60°E longitudes due to the SHIFT of the Inter-Tropical Convergence Zone and start blowing from SOUTHWEST to northeast due to the Coriolis force.This will lead to the development of the southwest monsoon.The Inter-Tropical Convergence Zone moves southward, and so the reversal of winds from northeast to SOUTH and southwest takes place during the winter season.This will leads to the development of northeast monsoons.