2D animation of the Asian Monsoon (2.8 MB Quicktime)
3D Animation of the Asian Monsoon (big - 4.5 MB Quicktime) (small - 2.3 MB Quicktime)
The monsoon starts over Southeast Asia early in March and April. Heavy monsoon rainfall is also found over South China before a monsoon sets up over the Indian monsoon region. In the middle of May, cross-equatorial winds become pronounced in association with heavy convective rainfall in the southern tip of the Indian subcontinent. The enire Indian monsoon region experiences the most rapid transition of circulations in May.
Strong low-level winds, the so-called Somali Jet, are continuously intensified throughout June, while progressing northward steadily. The heavy rainfall near the west coast of the Indian subcontinent is associated with high mountain terrain and abundant moisture supply transported by the Somali Jet. The northern part of the Bay of Bengal is known to have about the heaviest rainfall in the world during the summer monsoon period. The low-level cyclonic circulation east of the mountains may provide a favorable condition for the development of tropical depressions, where the westward propagating disturbances from the western Pacific are often intensified. The source of moisture for the heavy rains is not clear yet. However, the moisture evaporated from the Arabian Sea and the South Indian Ocean appears to be an important source.
In June, the monsoon rainbands continuously march northward over the East Asian region as well. While the total precipitation amount is not comparable to the tropical rainfall, the concentrated rainfall during the monsoon period, usually no longer than two weeks, is crucial for the agriculture over that region. The East Asian monsoon has different names as it progress northward; Mai-Yu in China, Baiu in Japan, and Changma in Korea. The failure of the monsoon often results in devastating drought over these countries.