Condensation and evaporation of water vapor in mixed aerosols of liquid droplets and ice: numerical comparison of growth rate expressions

Abstract

We compare four different H 2O mass flux descriptions in simulations of the evolution of mixed water/ice aerosol populations undergoing condensational growth. It is shown that the Maxwellian description, ignoring condensation heat release, overestimates the growth rates severely when compared with an exact numerical description. The well-known Mason equation predicts the growth rates somewhat better, but still in an inadequate manner as far as cloud drop formation is considered: after 100 s growth the drop radii are overestimated by up to a factor of 3 at −30°C. An analytical mass flux formulation by Lehtinen et al. (1998) ( J. Aerosol Sci. 29, 1035), on the other hand, compares very well with the exact description while requiring only one percent of computing time needed for the exact numerical calculations.