Modeling particle formation kinetics in mixed-phase clouds

A computational model for droplet and ice particle formation kinetics in mixed clouds is developed using the kinetic equations of condensation/coagulation formulated by Piskunov and Petrov (J. Aerosol Sci. 33 (2002) 647) for two-phase disperse systems. Alongside new kinetic equations, the model involves equations of mass and thermal balance, accounts for the difference in rates of vapor condensation above water and ice, uses actual condensation and coagulation growth rates, describes the phase transition dynamics. A method of x–T diagrams is suggested for visual treatment of the dynamics of condensation redistribution of material (distillation) from the water fraction to ice particles. The method allows easy graphic representation and study of the basic condensation process stages and prediction of the final state parameters. Criteria are found for the efficiency of methods for artificial action on a cloud system involving its seeding with ice-forming reagents, based on the effect of the redistibution of material. The developed numerical model is used for computation of the precipitation formation processes in the conditions of the Montana experiment of 07/19/1981 (J. Geophys. Res. 91 (01) (1986) 1231; J. Geophys. Res. 90 (D4) (1985) 60079).