Information

The rainfall distribution over Asia shows a sloping trend from the humid tropics to the interior of the continent. In many parts of Southeast Asia and India there can be between 1,000 and 3,000 mm annual rainfall, the highest amount in Asia. In Central Asia, the rainfall passes through the increasing hygric continentality and the lee of the Himalayas and back to partially less than 100 millimetres (Gobi desert). In the Arab region the influence of the descending air of the subtropical high pressure belt is strongly felt, and also results in annual rainfall amounts of 100 mm and below there.
The rainfall regime in Asia is determined by the major circulation elements of the atmosphere. In some areas north of the 40th Latitude, westerly winds are dominating. The "wandering cyclones " of the west wind drift, lose a lot of water vapour on their way from the coast of Europe into the interior of Asia and sometimes they dissolve completely. And so, the annual mean of the continent east of the Urals is relatively dry. The rainfall here is mainly a result of convective clouds which strongly heat the land masses in the summer. The term hygric continentality is a summer rainfall maximum.
South of the Tibetan Plateau and in East Asia, the westerly wind entropical regime is intertwined with the onshore trade wind regime. Those in the zenith position of the sun, shift in atmospheric circulation belts and lead to summer rainfall within the distribution area of this "East Asian monsoon".
In the equatorial regions of Malaysia, Indonesia and parts of the Philippines, the continuing influence of the Intertropical Convergence Zone (ITC) dominates with its year-round rainfall in the equatorial westerly wind regime.
The monsoon characterises the seasonal nature of weather in many parts of Southeast Asia and India. The seasonal change between the dry northeast winds from the interior of Asia in the winter and the humid summer air masses of the southwest monsoon, determines the rainfall on the subcontinent.
P. Frankenberg, A. Siegmund, D. Volz; Ü: C. Fleming