wind shear


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wind shear,

a sudden, drastic change in wind direction or speed over a comparatively short distance. Most winds travel horizontally, as does most wind shear, but under certain conditions, including thunderstorms and strong frontal systems, wind shear will travel in a vertical direction. Microburst wind shear is an extremely violent downward blast of air that hits the earth and radiates outward. With its sharp shifts in wind direction and relative wind speed, it can cause an aircraft to lose lift and crash, especially during takeoff or landing, when the slower speeds and closeness to the ground make altitude correction more difficult. Since 1996 all U.S. airliners have been required to be equipped with instruments that provide the pilot with advance warning of wind shear. See also weatherweather,
state of the atmosphere at a given time and place with regard to temperature, air pressure (see barometer), wind, humidity, cloudiness, and precipitation. The term weather
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 and windwind,
flow of air relative to the earth's surface. A wind is named according to the point of the compass from which it blows, e.g., a wind blowing from the north is a north wind.
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.

wind shear

[′win ‚shir]
(meteorology)
The local variation of the wind vector or any of its components in a given direction.

wind shear

wind shear
Vertical wind shear near the ground.
The rate of change in the wind velocity in space, considered as a vector. A vertical shear is a change in the wind velocity with height, whereas a horizontal shear is the change in the wind with the horizontal distance perpendicular to the flow.
References in periodicals archive ?
But industry experts say the suspected involvement of wind shear draws far more chilling parallels with the crash of a Delta Air Lines DAL.N Lockheed Tristar while on approach to Dallas airport in 1985 that killed 134 passengers and crew.
While it was too early to definitively say what caused the crash, Kajit Habnanonda, president of Orient-Thai Airlines, which owns One-Two-Go, also pointed to wind shear as a possible factor.
In general, the spikes in activity occurred when wind shear was weak.
If a six-month averaging interval is used, the alternation of the wind shear curvature will decrease [5,6].
The gradually sloping terrain of the Great Plains region helps produce strong wind shear that's ideal for tornado formation.
The KJ's low-power color radar provides excellent doppler ground mapping, weather, wind shear and skin-paint displays.
High volumes of surrounding room air are directed across the aerodynamic surface, resulting in a forceful airstream with minimal wind shear. EXAIR Corp., 1250 Century Circle North, Cincinnati, OH 45246.
The volcanic ash detector may also be suitable for sensing clear air turbulence and low-level wind shear.
The photographs' laconic titles evoke an expert's shorthand evaluations of the black-box tapes from these accidents: Spatial Disorientation (pilot error, induced); Touchdown (premature); Wind Shear (unforeseeable) (all works 2000).
The RDR-4B uses Doppler radar to detect wind shear - dangerous horizontal winds that occur when a thunderstorm's strong downdraft approaches the Earth's surface.
Wind shear detection and alarm, and detailed in-flight analysis of weather maximize airline profits and improve passenger comfort and safety.
Wind shear is one of the major banes of air travel, a killer held responsible for causing 18 crashes and 575 deaths since 1970.