A drainage wind flow model.

A method of predetermining drainage wind velocities is derived in the form of an incremental velocity model. The model requires the topographical data and a general description of surface roughness. Using these fixed inputs with the model yields velocity factors. Velocity factors are determined as a function of height above the terrain and elapsed time since the occurrence of the maximum surface temperature. The velocity factors multiplied by a cooling factor give velocities. Time or space mean velocity may be found by summation techniques. By computing velocity factors for several points within an area of concern, one can determine drainage flow patterns and pollutant movements for any given night.