Cumulus clouds - Numerical models, observations and entrainment

The first computer simulation of the organization phase of a buoyant atmospheric thermal is described. Although crude, it showed the spontaneous development of a rounded tight-gradient 'cap' and internal vortical circulation. The complexities involved in these 'field of motion' models in part motivated the development of entity models, based upon laboratory thermals. These one-dimensional models and their uses with observations are briefly described as well as their limitations. Finally, an application of Schlesinger's three-dimensional model to a GATE cumulus situation clarifies many apparently conflicting observations and postulates, thereby raising further challenging questions to be addressed jointly by the more sophisticated measuring and modeling tools available in the 1980's.