Recent Concepts about the Origin of Indian Monsoons

During the last five decades, the upper atmospheric circulation has been studied significantly, as a result of which meteorologists have raised certain doubts about the validity of the classical concept of the origin of Indian monsoon. It is now believed that the differential heating of land and sea cannot produce the monsoon circulation. More recent theories have laid greater emphasis on the circulation in atmosphere over the subcontinent and the adjoining areas. Apart from the upper atmospheric circulation, recent concepts rely heavily on the role of the Tibetan Plateau, jet streams, and the El-Nino (Southern Oscillation).

The data gathered by meteorologists after the Second World War have revealed that the origin and mechanism of monsoons are related to the following phenomena:

(i) The role of the Himalayas and Tibetan Plateau as a physical barrier and a source of high-level heat.

(ii) The circulation of upper air jet streams in the troposphere.

(iii) The existence of upper air circum polar whirl over north and south poles in the troposphere.

(iv) The differential heating and cooling of the huge landmass of Asia and the Indian and the Pacific Oceans.

(v) The occurrence of El-Nino in the South Pacific and Indian Oceans.