Abstract
Quasi-stationary approximations for the size distribution of aerosols have been derived by Friedlander using similarity arguments and dimensional analysis. In this paper they are rederived using an approach based on explicit models of the coagulation mechanisms that determine the spectrum of particle sizes. The primary aim is to cast Friedlander's work into a form suitable for Author generalization, but the new approach also clarifies criticism of the “sedimentation subrange.” The balance between coagulation growth and sedimentation loss postulated by Friedlander is interpreted differently and a new solution for this range is given. In contrast to the other subranges, the solution is not unique (granted the assumption that it is quasi-stationary), because it depends on the form of the externally imposed vertical gradient in number density. The new approach is also applied to a condensation subrange for the smallest particles.
