What causes the monsoon? The monsoon, which is essentially the seasonal reversal in wind direction, causes most of the rainfall received in India and some other parts of the world. The primary cause of monsoons is the difference between annual temperature trends over land and sea. The apparent position of the Sun with reference to the Earth oscillates from the Tropic of Cancer to the Tropic of Capricorn. Thus the low pressure region created by solar heating also changes latitude. The northeast and southeast trade winds converge in this low pressure zone, which is also known as the Inter tropical Convergence Zone or ITCZ. This low pressure region sees continuous rise of moist wind from the sea surface to the upper layers of the atmosphere, where the cooling means the air can no longer hold so much moisture resulting in precipitation. The rainy seasons of East Asia, sub-Saharan Africa, Australia and the southern part of North America coincide with the shift of ITCZ towards these regions.
