Random and rapid fluctuations in wind components, which determine the rate of turbulent dispersion or spread of the cloud. Typically expressed by the turbulent velocity (averaging about 1 m/s), which is the standard deviation of rapid fluctuations in wind speed (óu refers to fluctuations in the along-wind (x) direction, óv refers to fluctuations in the lateral (y) horizontal direction, and ów refers to fluctuations in the vertical (z) direction).
