Pub. date: 2008 | Online Pub. Date: April 25, 2008 | DOI: 10.4135/9781412963893 | Print ISBN: 9781412958783 | Online ISBN: 9781412963893| Publisher:SAGE Publications, Inc.About this encyclopedia
Heather K. Michon
RAIN IS COMPOSED of water droplets formed from vapor that has condensed in the Earth's atmosphere. Regular rainfall is vital to the functioning of the biosphere, and even minor fluctuations in the amount of rain can have substantial impact on the ecosystem. Climatologists believe that rainfall patterns are going to change dramatically as the atmosphere heats up in the coming decades, with potentially damaging consequences. Precipitation forms under three main types of conditions: convective uplift, frontal uplift, and orographie uplift. Convective uplift is common in the equatorial tropics and during the summer months. As the sun heats up the Earths surface, the humid, warm air rises into the atmosphere, cools, forms tall, unstable cumulonimbus clouds, and then releases its moisture in a quick downpour. Frontal uplifts are the result of cold and warm fronts colliding. This can take different forms. Fronts are transition zones between air masses of different temperatures. ...