翻訳と辞書 Words near each other ・ Reaping the Whirlwind ・ Reappearance ・ Reapportionment Act of 1929 ・ Reapportionment and Redistricting Committee (Georgia Senate) ・ Reappropriation ・ Rear ・ Rear (military) ・ Rear admiral ・ Rear admiral (Royal Navy) ・ Rear admiral (United States) ・ Rear Admiral William S. Parsons Award ・ Rear delt raise ・ Rear End ・ Rear end ・ Rear Enz ・ Rear flank downdraft ・ Rear Guard (video game) ・ Rear mid-engine, rear-wheel-drive layout ・ Rear Mirror ・ Rear Moth ・ Rear naked choke ・ Rear of the Armed Forces of the Russian Federation ・ Rear of the Year ・ Rear projection effect ・ Rear services ・ Rear Window ・ Rear Window (1998 film) ・ Rear Window (disambiguation) ・ Rear Window Captioning System ・ Rear-Admiral Eustațiu Sebastian-class corvette Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Rear flank downdraft ： ウィキペディア英語版 Rear flank downdraft The rear flank downdraft or RFD is a region of dry air wrapping around the back of a mesocyclone in a supercell thunderstorm. These areas of descending air are thought to be essential in the production of many supercellular tornadoes. Large hail within the rear flank downdraft often shows up brightly as a hook on weather radar images, producing the characteristic ''hook echo'', which often indicates the presence of a tornado.〔 == Formation == The rear flank downdraft can arise owing to negative buoyancy, which can be generated by cold anomalies produced at the rear of the supercell thunderstorm by evaporative cooling of precipitation or hail melting, or injection of dry and cooler air in the cloud, and by vertical perturbation pressure gradients that can arise from, vertical gradients of vertical vorticity, ''stagnation'' of environmental flow at an updraft, and pressure perturbations due to vertical buoyancy variations (which are partially due to hydrostatic effects), respectively.〔 Vertical pressure perturbations are generated by the buildup of pressure due to the vertical buoyancy, creating a pressure perturbation gradient. The subsiding air is generally dry and as it subsides the air warms adiabatically and can form a clearing in the cloud cover called a clear slot.〔 A clear slot can be observed to wrap around a tornado or form away from a tornado in the shape of a horseshoe. This clearing is most likely the formation of the hook echo region associated with tornado formation.〔 An RFD that originates in dry air and warms adiabatically can produce warmer observations out of the RFD at the surface. 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「Rear flank downdraft」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.