Cloud-Cloud Interactions and Their Roles in the Development of Convective Cloud Systems

Understanding the life cycle of cumulus clouds remains challenging due to limited knowledge of the factors governing initiation and growth processes. Cloud-cloud interactions—specifically how neighboring clouds influence each other—are a critical but underexplored aspect of evolution of cloud populations. Our key innovation lies in, using both realistic and idealized large-eddy simulations (LES), to identify and quantify competitive relationships among neighbouring  clouds as a fundamental driver of cloud population dynamics.

Realistic LES over land reveals a statistically significant pattern: growing clouds suppress the development of their immediate neighbors, suggesting competition for moisture among neighbouring cloudy updrafts. Idealized LES further uncovers that this competition is strongest during the decaying stage of clouds. During this stage, cloud-cloud  interactions reduce cloud depths but expand their horizontal extent through environmental moistening—a feedback that effectively reduces cloud spacing and intensifies competition. We also systematically establish the controlling factors of competitive strength by conducting multiple idealized LES simulations by varying: aerosol loading, inter-cloud distance, and surface forcing heterogeneity.

This work establishes cloud-cloud competition as a previously missing process in cumulus evolution theory. By mechanistically resolving how interactions redistribute moisture and energy, we provide a framework to understand population-scale organization. Our findings offer direct pathways to improve cumulus parameterizations in Earth system models, particularly in representing convective clustering and cloud lifetime effects.