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10. Shear with Temperature Inversion

a. A narrow zone of wind shear, and the turbulence it produces, is often encountered
when an aircraft goes up through or descends through a temperature inversion. The wind
speed and/or direction sometimes changes very quickly with altitude in this zone.

b. Wind shear that occurs with a strong temperature inversion near the ground is a
particular hazard to aircraft immediately after departing or just before landing at an airport.
Typically, heat from the ground radiates up and is lost during the night. This nighttime
radiational cooling causes a layer of cold air to form near the ground. The cold air, only a
few hundred feet thick, may be under a moving layer of warm air. Because of the windspeed
difference between the moving warm air and the still cold air, a narrow zone of wind shear
develops along the border. The degree of turbulence will depend on the speed of the warm
air since the cold air is still.

11. Shear Turbulence with Fronts

a. Because winds on either side of a front have different speed and direction, a shear
zone exists along the border of these winds.