It is an established fact that India’s annual production and economy depends largely on the annual monsoon rainfall. We have two seasonal rainfalls, the south-west monsoon and the north-east monsoon. The former lasts from the month of June to September and the latter from October to January. The timely onset of monsoon rains and their intensity greatly influence agricultural operations in the country and crop production. A normal monsoon year contributes greatly to boost our economy. Hence, it is important to understand the factors controlling monsoon rains and their effect in crop production.

Wind systems and monsoon: The greatest seasonal change in global air circulation is the development of monsoon. The word “monsoon”(Arabic word, meaning “season”) refers to wind systems that exhibit a pronounced seasonal reversal in direction. The best known and most pronounced monsoon circulation on the globe is found in southern and....