Plume Rise Predictions

Abstract

Anyone involved with diffusion calculations becomes well aware of the strong dependence of maximum ground concentrations on the “effective stack height,” h_e. For most conditions χ_max is approximately proportional to h_e⁻², as has been recognized at least since 1936 (Bosanquet and Pearson). Making allowance for the gradual decrease in the ratio of vertical to lateral diffusion at increasing heights, the exponent is slightly larger, say χ_max^~ h_e^−2.3. In inversion breakup fumigation, the exponent issomewhat smaller; very crudely, χ_max^~ h_e^−1.5 In any case, for an elevated emission the dependence of χ_max on h_e is substantial.