Formation of Shallow Cumulus Patterns Using a Simple Warm Cloud Precipitation Model

Abstract A simple model based on predator‐prey‐like dynamics using a system of four nonlinear ordinary differential equations is used to simulate the life cycle of shallow cumulus. By coupling this model across a two‐dimensional array and varying the cloud environment, we can simulate three common patterns of self‐aggregation seen in the maritime trades. These patterns include sugar, the small and randomly dispersed cumulus with little precipitation; gravel, small cumulus with frequent precipitation mostly associated with cold pools; and flowers, large clusters of cumulus surrounded by clear air. We find that clouds begin to cluster and organize as the environment grows more stable, the boundary layer deepens, latent heating increases, and clouds more strongly interact with their neighbors. Clouds in this model favor a flower‐type pattern as condensate pushes upward against the boundary layer and is forced to advect horizontally, while a gravel‐type pattern occurs in the presence of cold‐pool‐like circulations, consistent with observations.