The problem of diffusion in the lower atmosphere

Abstract

Abstract An account is given of a theory of atmospheric diffusion developed at Porton during the years 1932–38 in connexion with the problems of chemical warfare. It is shown that the theory leads to formulæ of the correct functional form but these only give results of the correct absolute magnitude when “extreme” values are admitted for the gustiness factors. With this proviso, the expressions developed are reliable for the calculation of atmospheric diffusion in the absence of very large gradients of temperature and provided that observations on the wind gradient are made above the layer in which the effects of surface roughness predominate. It is also shown that observations on the rate of evaporation from very small areas are not necessarily a reliable indication of the rate of removal of vapour from large areas, such as reservoirs and lakes.