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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.
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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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

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.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
References in periodicals archive ?
Vertical wind shear. Vertical wind shear is defined as the amount of change in wind direction and velocity with increasing altitude [5].
To understand the increased frequency in tornado outbreaks, the researchers looked at two factors: convective available potential energy, or CAPE, and storm relative helicity, which is a measure of vertical wind shear.
Positive Atlantic Multidecadal Oscillation phases, such as those seen from 1878-1899, 1926-1969 and since 1995 (Figure 2, right), are characterized by above-average far North and tropical Atlantic sea surface temperatures, below-average tropical Atlantic sea level pressures and reduced levels of tropical Atlantic vertical wind shear -- conditions known to create a more favorable environment for Atlantic hurricane formation and intensification.
DEVELOPMENT Working to derive algorithms that allow aerial gliders to ride without human help on vertical wind shear or on thermals.
A scientist at the Cyclone Warning Division, India Meteorological Department (IMD), said the system would continue to move north-northwestwards and further weaken into a tropical depression during the next 12 hours due to the colder seas, dry air and high vertical wind shear. "But, this will cause heavy rainfall in Oman, which will range from 100mm to 300mm," the official warned.
During an El Nino event, the vertical wind shear (i.e., the difference between the upper-level and lower-level winds) is increased across the North Atlantic basin.
And for many decades, Evan says, water in the Arabian Sea has been "really toasty." But winds in the upper and lower atmosphere there tend to blow briskly in opposing directions, in a phenomenon known as vertical wind shear. "This is the most hostile environment one could imagine for a hurricane," Evan explains.
In meteorology the vertical wind shear perspective is superior to other meteorological parameters, because it establishes the kind of physical cause and effect link between storm structure and the pre-storm environment that forecasters can readily apply when attempting to assess storm potential on any given day.
"We think that increased vertical wind shear in a warmer climate will prevent many storms from growing to hurricane force.
But the same climate change that is believed to cause higher SSTs also affects vertical wind shear.
Ahead of the cold front, the atmosphere was very unstable with favorable vertical wind shear, due in part to a warm front that stretched east-southeast from the area of low pressure.
If El NiEo were to develop, it would tend to lead to "more vertical wind shear in the Caribbean extending into the tropical Atlantic, tearing apart hurricanes as they are trying to develop and intensify."