  A cumulus cloud model which can explain the observed characteristics of warm
rain formation in monsoon clouds is presented. The model is based on classical
statistical physical concepts and satisfies the principle of maximum entropy
production. Atmospheric flows exhibit selfsimilar fractal fluctuations that are
ubiquitous to all dynamical systems in nature, such as physical, chemical,
social, etc and are characterized by inverse power law form for power (eddy
energy) spectrum signifying long-range space-time correlations. A general
systems theory model for atmospheric flows developed by the author is based on
the concept that the large eddy energy is the integrated mean of enclosed
turbulent (small scale) eddies. This model gives scale-free universal governing
equations for cloud growth processes. The model predicted cloud parameters are
in agreement with reported observations, in particular, the cloud dropsize
distribution. Rain formation can occur in warm clouds within 30minutes lifetime
under favourable conditions of moisture supply in the environment.
