Evolution of a precipitating cloud and cloud droplets

The evolution of a precipitating convective cloud was studied by a time-dependent numerical model in which for the simplification of dynamical framework the domain under consideration was expressed by three regions: inner region of cloud, outer region of cloud and environmental region. Clouds are assumed to have no ice-phase. The size distribution of water drops is described using five size-groups. Two types of cloud droplets (case A and case B) were given at cloud base. There are more small cloud droplets in case B than in case A. The slower production of raindrops in case B results in the later formation of a downdraft and rainfall than in case A. In consequence rainfall efficiency is lower in case B. These differences of both cases had a tendency to be larger in a less unstable atmosphere.