Wind Shear
The environmental wind field is also very important in determining what type of a thunderstorm could develop. Severe weather usually occurs when the change in horizontal winds (wind shear) is significant.
shearing instability"1. Same as Helmholtz instability. 2. A complex hydrodynamic instability phenomenon exhibited by a stratified shear flow.
Shear - see wind shear
Shelf Cloud - a low, horizontal wedge-shaped arcus cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms).
shear line - In meteorology, a line or narrow zone across which there is an abrupt change in the horizontal wind component parallel to this line; a line of maximum horizontal wind shear.
shield - See rain-gauge shield, radiation shield.
SHEAR
It is the rate of change over a short duration. In wind shear, it can refer to the frequent change in wind speed within a short distance. It can occur vertically or horizontally.
Shear - Variation in wind speed and/or direction) over a short distance. Shear usually refers to vertical wind shear, i.e.
Shear See wind shear.
Sheet lightning A fairly bright lightning flash from distant thunderstorms that illuminates a portion of the cloud.
SHEAR (WIND SHEAR)- Significant change in wind speed or direction with height. For severe weather this is most relevant if it occurs in the lower troposphere.
shear—See wind shear.
shower—Precipitation from a cumuliform cloud; characterized by the suddenness of beginning and ending, by the rapid change of intensity, and usually by rapid change in the appearance of the sky; ...
Back-sheared Anvil - [Slang], a thunderstorm anvil which spreads upwind, against the flow aloft. A back-sheared anvil often implies a very strong updraft and a high severe weather potential. (See Fig. 7, supercell.) ...
Wind Shear - See shear.
Wrapping Gust Front - A gust front which wraps around a mesocyclone, cutting off the inflow of warm moist air to the mesocyclone circulation and resulting in an occluded mesocyclone.
Wind shear - Any sudden change in wind speed or direction.
[Thunderstorms & Tornadoes] [Hurricanes] [Blizzards & Winter Weather] [Clouds] ...
WIND SHEAR The rate of wind speed or direction change with distance. Vertical wind shear is the rate of change of the wind with respect to altitude. Horizontal wind shear is the rate of change on a horizontal plane.
Wind shear - A changing of wind speed or direction with distance; vertical wind shear is changing of wind with respect to height.
Zonal - In the west-east direction.
Wind Shear
The rate at which wind velocity changes from point to point in a given direction (as, vertically).
Wind shear - a velocity gradient. The change in speed and direction over a set change in position of the observer.
Wind Shear The rate of change of wind speed and/or direction over a given distance. Also, see shear.
WIND SHEAR: The change of wind speed or direction with distance, usually vertical.
WIND WAVES: Short period and irregular waves created by the flow of air over the water.
Wind Shear- the change in wind direction; vertical wind shear is the change in wind speed with height.
Wind Wave- a wave that is caused by the action of wind on the surface of water.
Wind shear: The change of wind speed and/or direction in the atmosphere along a given direction.
Windsocks: Used to estimate wind speed and direction at airports.
wind shear: the rate of change of wind speed or wind direction over a short period of time and a short distance. Can occur vertically or horizontally.
wind vane: instrument used to measure wind direction.
zephyr any soft, gentle breeze.
WIND SHEAR -The change of wind speed or direction with distance or height.
WIND VANE- An instrument that determines the direction from which a wind is blowing.
WINDY - Sustained winds of 20 to 30 mph.
Wind shear The change in wind speed or direction with time or distance.
Wind vane An instrument used to monitor wind direction by always pointing into the wind.
Speed shear
The component of wind shear which is due to a change in wind speed with height, e.g., southwesterly winds of 20 knots at 10,000 feet increasing to 50 knots at 20,000 feet.
SHEAR TURBULENCE - Rough air caused by adjacent layers of air moving with different velocities.
SIMULATOR - A device set up to simulate flight. A flight simulator may be static or may actually move on a trailer.
Shear - It's just a variation in the wind speed and/or direction over a short distance.
Shortwave - It's basically a trough. It's an elongated area of low pressure. These can form stormy weather.
SHEAR - Changes of wind speed and / or direction along a horizontal or vertical path.
The shear created by a rapid change in wind direction with height.
DISCONTINUITY ...
wind shear- vertical eddies or waves of air resulting from one layer of air sliding over another moving at different speeds or directions.
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Combined Shear (CS) This WSR-88D radar product displays a combined radial and azimuthal shear of the mean radial velocity. It is available for all elevation angles.
Combined Shear Contour (CSC): This WSR-88D radar product is a contoured version of Combined Shear (CS) that is displayable alone or as an overlay on reflectivity or velocity products.
Directional shear
The component of wind shear which is due to a change in wind direction with height, e.g., southeasterly winds at the surface and southwesterly winds aloft.
wind shearA difference in wind speed or direction between two wind currents in the atmosphere.wind vaneAn instrument used to determine wind direction.
Wind shear A local variation of the wind vector or any of its components in a given direction. Wind sleeve Same as windsock. Wind sock A fabric cone attached to a metal ring and used to indicate wind direction, often at airfields.
LOW LEVEL WIND SHEAR: A local variation in the wind direction or speed. This condition can present danger to aircraft, especially at landing, when a sudden shift from headwind to tailwind can cause a rapid loss of airspeed and lift.
Transverse bands observed at low levels (called transverse rolls or T rolls) often indicate the presence of a temperature inversion (or cap) as well as directional shear in the low- to mid-level winds.
Storm RelativeMeasured relative to a moving thunderstorm, usually referring to winds, wind shear, or helicity.
Microbursts may induce dangerous horizontal/vertical wind shears, which can adversely affect aircraft performance and cause property damage.
Deformation ZoneThe change in shape of a fluid mass by variations in wind, specifically by stretching and/or shearing. Deformation is a primary factor in frontogenesis (evolution of fronts) and frontolysis (decay of fronts).
Is it building directly upwards, or sheared to one side? Is it possible to determine whether you are observing a single or multi-cell complex? Is any rotation observed in the cloud elements etc?
LLWS: Low Level Wind Shear.
LLGT, LTNG: Lightning.
LGTCC: Lightning Cloud To Cloud.
LGTCCCG: Lightning Cloud To Cloud, Cloud To Ground.
LGTCW: Lightning Cloud To Water.
LGTIC: Lightning In Cloud.
LST: Local Standard Time.
"M"
MB: Millibar.
where u* is the friction (or shear) velocity (m s-1), κ is von Karman's constant (~0.41), d is the zero plane displacement, z0 is the surface roughness (in meters), and φ is a stability term where L is the Monin-Obukhov stability parameter.
Barotropic systems are characterized by a lack of wind shear, and thus are generally unfavorable areas for severe thunderstorm development. See baroclinic zone.
Dispersion can be the result of molecular diffusion, turbulent mixing, and mean wind shear. The displacement or advection of polluted air by the mean wind is usually called transport rather than dispersion.
Here, v* is the friction velocity √(τ/ρ), where τ is the shear stress at the v = 0 plane and ρ is the density. k is the von Kármán constant, which has the value of 0.4, approximately.
The Severe Weather Threat (SWEAT) Index uses atmospheric stability, wind shear, and wind speeds aloft (taken from radiosonde reports).
They usually appear on the upwind side of a back-sheared anvil, and indicate rapid expansion of the anvil due to the presence of a very strong updraft. They are not mammatus clouds. See also cumuliform anvil and anvil rollover.
It is often found in the vicinity of the jet stream where large shears in the horizontal and vertical are found, although this turbulence is not limited just to jet stream locale.
(2) A mesoscale cyclone originating in or near a frontolyzing zone of horizontal wind shear, with radius of maximum sustained winds generally less than 30 miles.
The difference between wind velocity measured at two specific locations divided by the distance between those two positions; wind shear consists of a combination of speed shear and directional shear.
wind vane ...
A second type of subtropical cyclone is a mesoscale low originating in or near a frontolyzing zone of horizontal wind shear, with radius of maximum sustained winds generally less than 30 miles.
There must be little change in the wind speed between the upper and lower atmosphere, otherwise deep thunderstorms will be sheared (torn apart) before they can become organised.
[Slang] A thunderstorm anvil which spreads upwind, against the upper-level flow. A back-sheared anvil often implies a very strong updraft and hence a possibly severe thunderstorm.
Jet Stream
Flat tubular, quasi-horizontal, current of air generally near the tropopause, whose axis is along a line of maximum speed and which is characterized by great speeds and strong vertical and horizontal wind shears.
More violent severe thunderstorms form in areas with a strong vertical wind shear that forces the updraft into the mature stage, the most intense stage of the thunderstorm.
It is a sign of vertical wind shear, a favorable condition for severe storm development.TodayUntil sunset. TomorrowMidnight to midnight.TonightSunset to midnight.
 See also: Wind, Air, Storm, Surface, Cloud
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