On Size Distributions of Cloud Droplets Growing by Condensation: A New Conceptual Model

Abstract Observed turbulence and fluctuating microphysical properties of clouds lead the authors to assume that a cloud droplet size distribution results from a large number of random events associated with turbulence and to consider a droplet system with fluctuating cloud droplet size distributions constrained by conservation laws. This assumption in turn suggests multiplicity rather than uniqueness of cloud droplet size distributions, that is, different cloud droplet size distributions occurring with different probability. The authors argue from a system point of view that two characteristic cloud droplet size distributions can be identified without knowing the specific probability of occurrence. The maximum likelihood cloud droplet size distribution is obtained by applying Shannon’s maximum entropy principle; the minimum likelihood cloud droplet size distribution is obtained by studying the functional relationship between a cloud droplet size distribution and the corresponding energy change to form suc...