Friction in the Boundary Layer - eddy viscosity

  • Eddy viscosity refers to the internal friction generated as laminar (smooth, steady) flow becomes irregular and turbulent as it passes over irregularities on the surface (trees, buildings, mountains, etc)

  • Eddy motions created by obstructions are commonly referred to as mechanical turbulence

  • mechanical turbulence produces a frictional affect (drag) on the air flow that is much larger than caused by molecular viscosity


After a winter snowstorm, Cheyenne, Wyoming reports a total snow accumulation of 48 cm, while the maximum depth in the surrounding countryside is only 28 cm. If the storms intensity and duration were practically the same for a radius of 50 km around Cheyenne, explain why Cheyenne received so much more snow.