Thursday, June 29, 2006


A thunderstorm, or an electrical storm, is a form of weather characterized by the presence of lightning and its attendant thunder. It is usually accompanied by copious rainfall, hail, or rarely, snowfall in the winter months, sometimes termed thundersnow.

Thunderstorms occur throughout the world, even in the polar regions, with the greatest frequency in tropical rainforest areas, where they may occur nearly daily. Kampala and Tororo in Uganda have each been mentioned as the most thunderous places on Earth, an accolade which has also been bestowed upon Bogor on Java, Indonesia. In temperate regions, they are most frequent in spring and summer, though can occur in cold fronts at any time of year. Probably the most thunderous region outside of the Tropics is Florida. During the summer, violent thunderstorms are an almost daily occurrence over central and southern parts of the state. The most powerful and dangerous severe thunderstorms also occur over the USA, particularly in the Midwest and the southern States. These storms can produce very large hail and powerful tornadoes. Thunderstorms are rare along the West Coast of the United States, though they do occur more frequently in inland areas.

Thunderstorms form when significant condensation—resulting in the production of a wide range of water droplets and ice crystals—occurs in an atmosphere that is unstable and supports deep, rapid upward motion. This often occurs in the presence of three conditions: sufficient moisture accumulated in the lower atmosphere, reflected by high dewpoint temperatures; a significant fall in air temperature with increasing height, known as a steep adiabatic lapse rate; and a force such as mechanical convergence along a cold front to focus the lift.


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