Monsoon

A monsoon is any wind that reverses direction seasonally. With the change in the direction of the wind, there is usually a change in precipitation. The name is usually associated with the rainy phase of the monsoon winds. They are caused by the uneven heating and cooling of the land and sea and are similar to daily land and sea breezes that are commonly experienced at the beach.

Monsoons occur in many parts of the globe, but the most famous is the Indian monsoon wind. The word monsoon is an adoption of the Arabic word mausim, which means season. For centuries, Arab sailors took the seasonal mausim as a wind that would carry them to India and beyond. The term was originally applied to the Indian monsoon, but as the phenomenon came to be studied more thoroughly, the term monsoon has been applied to other annual weather cycles in both tropical and subtropical regions. It has also been applied to evidence of weather patterns in the geologic past, such as a monsoon system over the prehistoric supercontinent of Pangaea and to some extreme continental climate patterns.

Monsoons can occur in the summer or winter months. Those occurring in the summer usually blow as a prevailing wind from a westerly direction. The westerly monsoons usually bring heavy rainfall as the rising air comes from the ocean and brings moisture that falls as rain. In the winter months, monsoon winds usually blow in an easterly direction. Since easterly winds usually blow from land, they typically bring dry weather. They may also bring drought as the easterlies diverge or shift about. The intensity of monsoons varies annually, and the strength of annual monsoons is affected by the Earth’s total climate system. Since the amount of available energy varies, the system has different outputs, such as the strength of the monsoons, which results in variable amounts of annual rainfall.