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Encyclopedia > Vertical draft
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An updraft or downdraft(air pocket) is the vertical movement of air as a weather related phenomenon. Commonly, one of two forces causes the air to move. Localized regions of warm or cool air will exhibit vertical movement. A pocket of warm air will typically be less dense than the surrounding region, and so will rise until it reaches air that is either warmer or less dense than itself. The converse will occur for a mass of cool air, and is known as subsidence. This movement of large volumes of air, especially when regions of hot, wet air rise, can create large clouds, and is the main cause of thunderstorms. Drafts can also be created by low or high pressure regions. A low pressure region will attract air from the surrounding area, which will move towards the center and then rise, creating an updraft. The reverse will naturally occur in a high pressure region, as air moves away from the high pressure center. Image File history File links Please see the file description page for further information. ... This article is about the atmospheric phenomenon. ... AIR is a three-letter abbreviation with multiple meanings, as described below: The Annals of Improbable Research, a monthly magazine devoted to scientific humour All India Radio - Indias Government Radio service AIR, a popular electronica band from France. ... Weather is an all-encompassing term used to describe all of the many and varied phenomena that can occur in the atmosphere of a planet. ... A road destroyed by subsidence and shear. ... A rolling thundercloud over Enschede, The Netherlands. ...

Notable effects

Updrafts and downdrafts are some of the main causes of in-flight turbulence in planes, and are one reason airlines try to avoid regions of bad weather. Extreme cases, known as downbursts and microbursts are responsible for many airplane crashes. The crash of Delta Air Lines Flight 191 on their final approach leg before landing in 1985 was presumably caused by a microburst, and prompted the Federal Aviation Administration to research and deploy new storm detection radar stations at some of the major airports. A downburst is a column of sinking air that is capable of producing damaging straight-line winds over 100 mph, similar to, but distinguishable from tornadoes. ... A photograph of the surface curl soon after an intense microburst impacted the surface A microburst is a very localized column of sinking air, producing damaging divergent and straight-line winds at the surface that are similar to but distinguishable from tornadoes which generally have convergent damage. ... Delta Air Lines Flight 191 - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... This article is about the year. ... The Federal Aviation Administration is the entity of the United States government which regulates and oversees all aspects of civil aviation in the U.S. // Activities Along with the European Joint Aviation Authorities, the FAA is one of the two main agencies worldwide responsible for the certification of new aircraft. ...

Downbursts can cause extensive localized damage, similar to that caused by tornados. Downburst damage can be differentiated from that of a tornado because the resulting destruction is circular and radiates away from the center. Tornado damage radiates inward, towards the center of the damage. Union City, Oklahoma tornado (1973) A tornado is a violently rotating column of air which is in contact with both a cumulonimbus (or, in rare cases, cumulus) cloud base and the surface of the earth. ...

External links

  • National Science Digital Library - Downdraft
  • the Microburst Windshear
  • StormWiki



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