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A waterspout is an intense columnar vortex (usually appearing as a funnel-shaped cloud) that occurs over a body of water. They are connected to a towering cumuliform cloud or a cumulonimbus cloud. In the common form, it is a non-supercell tornado over water.〔 While it is often weaker than most of its land counterparts, stronger versions spawned by mesocyclones do occur. Most waterspouts do not suck up water; they are small and weak rotating columns of air over water.〔 While waterspouts form mostly in the tropics and subtropical areas,〔 other areas also report waterspouts, including Europe, New Zealand, the Great Lakes and Antarctica. Although rare, waterspouts have been observed in connection with lake-effect snow precipitation bands. Waterspouts have a five-part life cycle: formation of a dark spot on the water surface, spiral pattern on the water surface, formation of a spray ring, development of the visible condensation funnel, and ultimately decay. ==Formation== Waterspouts exist on a microscale, where their environment is less than two kilometers in width. The cloud from which they develop can be as innocuous as a moderate cumulus, or as great as a supercell. While some waterspouts are strong and tornadic in nature, most are much weaker and caused by different atmospheric dynamics. They normally develop in moisture-laden environments as their parent clouds are in the process of development, and it is theorized they spin as they move up the surface boundary from the horizontal shear near the surface, and then stretch upwards to the cloud once the low level shear vortex aligns with a developing cumulus cloud or thunderstorm. Weak tornadoes, known as landspouts, have been shown to develop in a similar manner.〔 〕 More than one waterspout can occur in the same vicinity at the same time. As many as nine simultaneous waterspouts have been reported on Lake Michigan.〔 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「Waterspout」の詳細全文を読む スポンサード リンク
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