monsoon (redirected from Monsoon cycle)

monsoon (mŏnsn) [Arab., mausium=season], wind that changes direction with change of season, notably in India and SE Asia. To a lesser degree, monsoonal winds also develop in portions of all other continents except Antarctica. The change of wind direction is caused by the differences in temperatures of landmasses in contrast to that of oceans. For example, the dry, or winter, monsoon of Asia is largely the result of an area of high pressure that develops over S Siberia. From this area dry winds blow outward, crossing India from northeast to southwest and SE Asia from north to south. The wet, or summer, monsoon is caused by low pressure that develops over S Asia as the landmass warms. Moisture-laden air over the oceans is drawn toward this center of low pressure. The air cools as it ascends the slopes of mountain barriers; it can no longer retain moisture, resulting in heavy rainfall.

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monsoon

Major wind system that seasonally reverses its direction (e.g., one that blows for six months from the northeast and six months from the southwest). The most prominent examples occur in Africa and southern Asia. The primary cause of monsoons is the difference between annual temperature trends over land and sea. Seasonal changes in temperature are large over land but small over oceans. A monsoon blows from cold toward warm regions: from sea toward land in summer and from land toward sea in winter. Most summer monsoons produce copious amounts of rain; winter monsoons tend to cause drought.