SUPERSATURATION AND TIME OF PHASE RELAXATION IN MIXED CLOUDS (THEORETICAL CONSIDERATION)

A. V. Korolev and I. P. Mazin

The rate of cloud-water transition from vapor to condensed phases and vice versa is determined mainly by relative humidity (or supersaturation) and by the time of phase relaxation, which in turn depends on cloud microstructure and vertical motions. For adiabatically ascending parcels in liquid clouds, the quasi-steady supersaturation and relaxation time were found 30 years ago [5, 13]. Phase transition in ice clouds was described in [22]. This work presents the analytical consideration of a general case of phase transition in mixed phase clouds. The time of mixed cloud glaciation is estimated here. The cloud glaciation parameter indicating the condition for stable coexisting of droplets and ice particles in mixed clouds, is introduced. The results obtained help to understand the high frequency of occurrence of mixed phase clouds observed in the troposphere.