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A microburst is a small downdraft that moves in a way opposite of a tornado. Microbursts are extremely hazardous to aircraft. Microbursts are found in strong thunderstorms .〔http://news.discovery.com/earth/weather-extreme-events/what-is-a-microburst-140515.htm〕 Within a thunderstorm there are two types of microbursts: wet microbursts and dry microbursts. They go through three stages in their life cycle: the downburst, outburst, and cushion stages. The scale and suddenness of a microburst makes it a great danger to aircraft due to the low-level wind shear caused by its gust front, with several fatal crashes having been attributed to the phenomenon over the past several decades. A microburst often has high winds that can knock over fully grown trees. They usually last for a couple of seconds to several minutes. == History of term == The term was defined by mesoscale meteorology expert Ted Fujita as affecting an area in diameter or less, distinguishing them as a type of downburst and apart from common wind shear which can encompass greater areas.〔Glossary of Meteorology. (Microburst. ) Retrieved on 2008-07-30.〕 Fujita also coined the term macroburst for downbursts larger than .〔Glossary of Meteorology. (Macroburst. ) Retrieved on 2008-07-30.〕 A distinction can be made between a wet microburst which consists of precipitation and a dry microburst which typically consists of virga.〔Fernando Caracena, Ronald L. Holle, and Charles A. Doswell III. (Microbursts: A Handbook for Visual Identification. ) Retrieved on 2008-07-09.〕 They generally are formed by precipitation-cooled air rushing to the surface, but they perhaps also could be powered from the high speed winds of the jet stream deflected toward the surface by a thunderstorm or by dynamical processes (see rear flank downdraft). Microbursts are recognized as capable of generating wind speeds higher than . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「microburst」の詳細全文を読む スポンサード リンク
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