Diffusion of Stack Gases in Very Stable Atmospheres

Abstract

Smoke plumes emitted from elevated sources during inversion conditions and characterized by negligibly small settling rates remain aloft for many miles over fairly flat terrain. Photographs of oil-fog plumes taken at the Brookhaven National Laboratory are presented to show the non-isotropic character of diffusion during conditions of strong stability.

Since relatively rapid dilution occurs within the first few meters of a stack, the diffusion problem is treated as a two-phase problem. The first phase may be termed the aerodynamic phase, the second phase, the meteorological phase.

The classical diffusion equation is re-examined for possible application in the inversion case. If concentrations of the effluent within the first one or two kilometers of the source are desired, it is desirable to treat the source as an area source of finite concentration rather than a point source of infinite concentration.