Some elements of the statistical theory of turbulence are briefly reviewed from the viewpoint of their application to micrometeorology.Several relations concerning turbulent diffusion in a field of homogeneous and isotropic turbulence are then discussed. The mean-concentration distributions for an instantaneous and for a continuous point-source are investigated, with particular attention to the case when the intensity of turbulence cannot be considered as small in comparison with the mean velocity. The time history of mean-concentration distributions in a diffusing spherical cloud is then studied.
The relation between Fick's differential equation of diffusion and the statistical theory of turbulence is studied, and the limits of validity of Fick's equation are determined. Finally, the relation between the coefficient of eddy diffusion and the statistical characteristics of turbulence is discussed.