The south Asian monsoon

The yearly cycle of weather events across southern Asia, the Indian Ocean and other coastal zones bordering upon its waters is significant within the dynamic climatology of the general circulation. It is also highly significant by reason of its impact upon the lives of hundreds of millions of people especially in the Indian subcontinent. The greatest effect on human life and economy is exercised through the annual cycle of precipitation, which can be conveniently expressed through rainfall means and rainfall variability. The variability of the rains is, in part, a function of the length of the monsoon rainy season. Traditionally, the south Asian monsoon has been explained in terms of an enormous ‘land-sea breeze’ circulation system. Modern views are rather different. They hold that the Asiatic monsoon regime is a consequence of complex interactions of planetary and regional factors both at the surface of the earth and in the upper troposphere.