Ice Nucleation by Aerosol Particles. Theory of Condensation-Freezing Nucleation

Abstract

A probabillstic theory of heterogeneous condensation-freezing nucleation is developed for monodisperse aerosol particles. An assumption is made that the physical process is heterogeneous condensation nucleation followed by heterogeneous freezing nucleation. The theory is expanded to a polydisperse system. Computed results based on the theory show a striking resemblance particularly in shape with experimental data. Using the theory and an empirical expression for deposition nucleation, the ice nucleation probability of pure AgI particles is reconstructed on the supersaturation-supercooling plane. Importance of proper environmental conditions free from transient supersaturation for condensation-freezing nuclei measurement and necessity of condensation-freezing nucleation modeling are pointed out.