Introduction

Turbulence results from eddies or fluctuations in wind speed or direction. This figure shows streamlines associated with a vertically propagating mountain wave. Also note the low-level rotor circulation downstream of the mountains. Both the vertically propagating wave and the rotor circulation create turbulence.

When turbulence is encountered, aircraft typically experience an irregular series of sharp bumps, which may impact their stability and motion. The degree of impact depends on aircraft characteristics (size, airspeed, etc.) as well as the intensity of the turbulence encountered. The intensity of turbulence is primarily dependent on horizontal and vertical wind shear and the atmospheric stability in the flight layer, characteristics that can be assessed via a skew-T diagram when forecasting for aviation interests.

This section will examine the forecast methodology for using a Skew-T to predict turbulence. For more information on mountain waves, see the COMET module Mountain Waves and Downslope Winds (http://meted.ucar.edu/mesoprim/mtnwave).

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