Dynamics of the cloud-environment interface and entrainment in small cumuli: two-dimensional simulations in the absence of ambient shear.

Abstract

We employ a two-dimensional numerical model with interacting nested domains to simulate the evolution of a small nonprecipitating cumulus cloud in the absence of shear. Grid nesting permits the use of a realistic boundary layer forcing to initiate cloud growth and, at the same time, the specification of very high spatial resolution in the vicinity of the cloud. Our simulations indicate that entrainment in a growing cumulus is a well-ordered laminar phenomenon driven by inviscid dynamical processes rather than a turbulent phenomenon driven by mixing.-from Authors