The Atmospheric Boundary Layer

This chapter studies the aspects of atmospheric boundary layer (ABL) flow of interest from a structural engineering viewpoint. It concerns the dependence of the wind speed on averaging time. The chapter presents the equations of mean motion in the ABL. It pertains to horizontally homogeneous flows over flat uniform surfaces, and contains, respectively, theoretical as well as empirical results on the dependence of wind speeds on height above the Earth's surface, and the structure of atmospheric turbulence. The chapter concerns horizontally non‐homogeneous flows. Horizontal non‐homogeneities of atmospheric flows are due either to conditions at the Earth's surface (e.g., changes in surface roughness, topographic features) or to the meteorological nature of the flow (as in the case of tropical cyclones, thunderstorms or downbursts). In current structural engineering practice, it is assumed that flow models used for synoptic storms are acceptable for hurricanes and thunderstorms as well.