The effect of meteorological variables upon the vertical and temporal distributions of atmospheric radon

Hourly values of radon concentrations were obtained simultaneously at four levels above ground up to 39.9 meters on the Argonne Meteorology Tower on three separate days. Twenty-seven consecutive hourly measurements were made on the first two days, and 17 on the third. Radon samples were obtained by adsorption on activated charcoal and were measured by means of scintillation counters. This technique, developed at Argonne, allowed direct measurement of radon instead of the common procedure of calculating radon values from measurements of daughter products. The large amount of meteorological data routinely obtained at the Argonne Meteorology Laboratory makes it possible to carry out detailed case studies on the relationship between radon concentration and the meteorological variables. This work has provided information on the heterogeneity of the horizontal distribution of radon. An inverse fumigation phenomenon was also observed. Under very stable nighttime conditions with light winds the radon concentrations observed at the top of the tower remained very low—about the same as during the daytime. Shortly after sunrise, with an increase in vertical mixing, the concentrations rose sharply. At a height of about 5.72 meters the radon concentrations on the clear nights ware larger by a factor of 20 than concentrations on the clear days. During cloudy conditions nighttime values were about twice as large as daytime values.