THE DISPERSION OF HOT GASES IN THE ATMOSPHERE

Abstract

The problem of the dispersion of a stream of hot gas from a point is considered. It is shown that a plausible assumption concerning the mechanism of entrainment of air by the jet leads to simple expressions for the mean temperature and mean velocity of a jet of hot air rising in a calm atmosphere of uniform potential temperature. The theoretical expressions are shown to agree with the laboratory measurements of Schmidt, and it is found that the coefficient of diffusion for these conditions is of the same order of magnitude as that which is derived from the large-scale spreading of cold smoke in the atmosphere. Finally, an approximate solution is given for the shape of the plume from a hot source in a horizontal wind, and it is demonstrated that the reduction of maximum concentration at ground level, caused by adding heat to the effluent from a stack, is directly proportional to the strength of the heat source and inversely proportional to the height of the chimney and the cube of the horizontal wind speed.