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. Image File history File links Download high resolution version (1220x1648, 1103 KB) Summary This is a photograph of a microburst (small, intense downburst). ... Image File history File links Download high resolution version (1220x1648, 1103 KB) Summary This is a photograph of a microburst (small, intense downburst). ... Union City, Oklahoma tornado (1973) A tornado is a violent spinning storm typically shaped like a funnel with the narrow end on the ground. ...

The term was defined by severe weather expert Tetsuya Theodore Fujita as affecting an area 4 km (2.5 mi) in diameter or less, distinguishing them as a type of downbursts and apart from common wind shear which can encompass greater areas. Dr. Fujita also coined the term macroburst for downbursts larger than 4 km (2.5 mi). Tetsuya Theodore Fujita (藤田哲也, October 23, 1920–November 19, 1998) was one of the great severe storms researchers of the twentieth century. ... 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. ... Wind shear is a difference in wind speed and/or direction between two points in the atmosphere. ...

A distinction can be made between a wet microburst which consists of precipitaiton and a dry microburst which consists of virga. 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 to the surface in a thunderstorm (see downburst). Virga is a meteorologic term for precipitation that falls from a cloud but evaporates before reaching the ground. ... Jet streams are fast flowing, relatively narrow air currents found in the atmosphere at around 12 km above the surface of the Earth, just under the tropopause. ... A roll cloud associated with a heavy or severe thunderstorm over Enschede, The Netherlands. ... 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. ...

Microbursts are recognized as capable of generating wind speeds higher than 75 m/s (168 mph; 270 km/h).

Danger to aircraft

See also: downbursts 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. ...

The scale and suddenness of a microburst makes it a great danger to aircraft, particularly those at low altitude which are taking off and landing. The following are some fatal crashes that have been attributed to microbursts in the vicinity of airports:

• Delta Air Lines Flight 191
• Eastern Flight 66
• Pan Am Flight 759
• USAir Flight 1016

Delta Air Lines Flight 191 - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Eastern Airlines Flight 66, a Boeing 727-225 with registration number N8845E, was operating New Orleans-Moisant-New York Kennedy on the afternoon of June 24, 1975. ... Pan Am Flight 759 soon after crashing in Kenner, Louisiana On July 9, 1982, Pan American World Airways, Inc. ... USAir Flight 1016 was a regularly scheduled flight between Columbia, South Carolina and Charlotte, North Carolina. ...

References

• Fujita, T.T. (1981). "Tornadoes and Downbursts in the Context of Generalized Planetary Scales". Journal of the Atmospheric Sciences, 38 (8).
• Wilson, James W. and Roger M. Wakimoto (2001). "The Discovery of the Downburst - TT Fujita's Contribution". Bulletin of the American Meteorological Society, 82 (1).

Tetsuya Theodore Ted Fujita (藤田哲也 Fujita Tetsuya, October 23, 1920–November 19, 1998) was one of the great severe storms researchers of the twentieth century. ... The American Meteorological Society (AMS) promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. ...

See also

• Air safety
• Downdraft

// Institutions Certification In most countries, civil aircraft have to be certified by the civil aviation authority (CAA) to be allowed to fly. ... A downdraft is downward moving air, usually the direct result of air convection within the thunderstorm. ...

External links

• The Semi-official Microburst Handbook Homepage (NOAA)
• Microbursts (WW2010) (University of Illinois)
• Taming the Microburst Windshear (NASA)