The Effects of Shallow Cumulus Cloud Shape on the Cloud-Cloud Interactions and Cloud-Environment Mixing

Cloud lifecycles are influenced by interactions among clouds and surroundings. Cloud shape, dictating the length of cloud boundaries, affects these interactions. This study uses a large eddy simulation linking cumulus cloud shape with lateral boundary processes. Two shape parameters are used: one reflects the areal cloud mask aspect ratio, and the other gauges cloud boundary wiggling. Shallow cumulus clouds evolve with increased wiggling and minimal aspect ratio changes in their lifecycles. Wiggling-driven perimeter growth spurs cloud-cloud interactions, distinct from aspect ratio-driven perimeter growth, favoring splitting over merging. Small cloud-shell differences are associated with wiggly clouds, suggesting strong entrainment-mixing. Findings emphasize considering cloud shapes for understanding and predicting cloud growth.