Wind Speed

Wind is the bulk movement of air. Wind is caused by differences in the atmospheric pressure. When a difference in atmospheric pressure exists, air moves from the higher to the lower pressure area, resulting in winds of various speeds. Globally, the two major driving factors of large-scale wind patterns are the differential heating between the equator and the poles and the rotation of the planet.

Wind Gust

A wind gust is a sudden, brief increase in the speed of the wind followed by a lull. Gusts at the ground are caused by either turbulence due to friction, wind shear or by solar heating of the ground.

Storm Motion

Storm motion is the predicted speed and direction of storms occurring over an area.

Storm Relative Helicity

Storm relative helicity is a measure of the potential for cyclonic updraft rotation.

Ventilation Rate

Ventilation Rate is the product of mixing height (the height above the surface throughout which a pollutant such as smoke can be dispersed) and transport wind (the average wind speed throughout the depth of the mixed layer). It represents the ability of the boundary layer to get rid of pollution. When ventilation rate values are low, there is not much mixing potential and surface air quality suffers.

Momentum Flux

Momentum flux is a measure of the rate of transfer of momentum across a unit area.

Vertical Velocity

A measure of the upward motion of air in the atmosphere. Since pressure decreases with height, negative vertical velocity values indicate rising motion in the atmosphere, and positive values indicate sinking air. When combined with high moisture levels, high vertical velocity indicates the potential for heavy rainfall.

Vertical Speed Shear

Vertical speed shear is the variation in wind over vertical distances. Strong vertical speed shear within the troposphere inhibits tropical cyclone development, but helps to organize individual thunderstorms into longer life cycles which can produce severe weather.

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