Climate

Asia's interior, far removed from the tempering influence of the oceans, cools rapidly in winter and becomes extremely cold. From this heartland bitterly cold, dry air streams out in all directions. During summer, the situation is reversed. The land heats rapidly, causing the air to rise and be replaced by cooler, moisture-laden air from the oceans. This seasonal reversal of the wind is known as the monsoon. Asia's high mountains are important climatically, for they act as barriers to the passage of air masses. Along some coasts the windward slopes of the mountains are exceptionally rainy; their leeward slopes are dry.

Northern Asia has a severe continental climate. Though often divided into several types—such as polar, sub-polar, middle-latitude steppe, and middle-latitude desert—it is everywhere marked by long, cold winters; warm to hot summers; and little precipitation. The coldest place on earth, excluding Antarctica, is the Verkhoyansk region of northeast Siberia, where January temperatures average -58° F. (-50° C.).

Subtropical and tropical conditions prevail throughout most of India and Indochina. Winters are mild, both because of the southerly latitude and because cold air masses are blocked by mountains, particularly the Himalayas. The summer monsoon is most pronounced in India, where strong southwesterly winds blow inland from the sea, giving abundant rainfall, especially in mountainous areas along the coast.

In extreme southeastern Asia, notably Malaysia and Indonesia, the climate is tropical and rainy. There are no seasons; the weather is always hot and humid. Southern China is subtropical and moist the year long. Prevailing in northern China is a continental kind of climate, with moderately cold winters and hot summers.

Dry climates with extremely hot summers predominate throughout southwest Asia. Baghdad, in Iraq, for example, has a July average temperature of 93° F. (34° C.) and receives only 6 inches (150 mm) of rain annually. Winters vary enormously with latitude and elevation. As in all steppe and desert regions, there are great daily variations in temperature. Along the Mediterranean coast, the climate is tempered by the sea. The narrow coastal belt has moderate amounts of rainfall, all of it falling in winter.