ch ao - d yn / 9 60 90 11 18 S ep 1 99 6 Coupled Map Modeling for Cloud Dynamics

A coupled map model for cloud dynamics is proposed, which consists of the successive operations of the physical processes; buoyancy, diusion, viscosity, adi-abatic expansion, fall of a droplet by gravity, descent ow dragged by the falling droplet, and advection. Through extensive simulations, the phases corresponding to stratus, cumulus, stratocumulus and cumulonimbus are found, with the change of the ground temperature and the moisture of the air. They are characterized by order parameters such as the cluster number, perimeter-to-area ratio of a cloud, and Kolmogorov-Sinai entropy. Cloud dynamics plays an important role in the climate system, weather forecast, geo-physics and so on. However this elementary process in meteorology is very much complicated because it consists of dierent time and space scales and the phase transition from liquid to gas is coupled with the motion of atmosphere. Even if the ow of the atmosphere were known with accuracy using Navier-Stokes equation, we could not discuss the 3