Monsoon

A monsoon is a seasonal change in the direction of the prevailing wind. This wind shift typically brings about a marked change in local weather. Monsoons are often associated with rainy seasons in the tropics (the areas of Earth within 23.5° latitude of the equator) and the subtropics (areas between 23.5° and about 35° latitude, both north and south). In these areas, life is critically dependent on the monsoon rains. A weak monsoon rainy season may cause drought, crop failures, and hardship for people and wildlife. The central role that monsoons play in determining climates around the world has made their study a high priority for meteorologists.

Many parts of the world experience monsoons to some extent. Probably the most famous are the Asian monsoons, which include the distinctly different monsoons that affect India, north China, and Japan, and south China and southeast Asia. Monsoons also affect portions of central Africa, where their rain is critical to supporting life in the area south of the Sahara Desert. Lesser monsoon circulations affect parts of the southwestern United States. These summer rainy periods bring much needed rain to the dry plateaus of Arizona and New Mexico.