WIND SHEAR

n. sudden change in the direction and momentum of a wind pattern (especially a shift from horizontal breezes to vertical breezes)

Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Wind shear can be broken down into vertical and horizontal components, with horizontal wind shear seen across weather fronts and near the coast, and vertical shear typically near the surface, and sometimes at higher levels in the atmosphere.
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See shear .

A change in wind speed and/or wind direction in a short distance resulting in a tearing or shearing effect. It can exist in a horizontal or vertical direction and occasionally in both.