Lateral dispersion in light-wind stable conditions

At downwind distances of 400 m or less, the angular standard deviation σθc of the lateral distribution of pollutants released from a point source over a given time period is shown to equal the standard deviation σθ , of the wind direction fluctuations observed over the same time period. Data taken during light wind, stable conditions at two field sites (Idaho falls, ID, and Oak Ridge, TN) are used in the analysis. This relation is most reliable if the pollutant concentration distribution is observed on a circle at constant distance from the source (i.e., on a polar coordinate system)