Abstract
The liquid water content of the atmosphere is studied on the basis of the differential equations of eddy exchange of total heat content (sensible plus latent heat) and total water content (vapour plus liquid water in form of droplets). We arrive at an equation of liquid water content which permits quantitative comparisons between different atmospheric processes of liquid water concentration, some of these being well known-for instance the adiabatic cooling, and the radiative cooling—others being mostly disregarded—such as the turbulent mixing and the vertical variation of the intensity of eddy exchange. We obtain support for the theory, as it relates to the distinction between the effects of mixing and radiation, by means of statistics of fogs. Finally, a classification of fogs is shown on the basis of our conclusions.