Boundary layer
Winds in the Central Plains region of the U.S. are variable on both short (minutes) and long (days) time scales. Variations in wind speed result in variations in power output from wind farms, which poses difficulties incorporating wind power into an integrated power system. Wind turbines are driven by boundary layer winds, those that occur near the surface of the earth, at around 300 feet. Boundary layer winds are controlled by wind in the higher free atmosphere and have turbulence due to interaction with surface features such as trees, hills, and buildings. Short term or high frequency variations are due to this turbulence in the boundary layer.