资源环境科技发展态势分析平台

A new model that resolves cloud drop size with thousands of bins is developed to simulate the growth of cloud drops by collision. The model is then evaluated with the analytic solution, showing that the model is quite accurate. Finally, the model is extended to properly incorporate the effect of radiation on drop growth. Model results reveal that warm rain can form within half an hour once the radiative effect is taken into account. Such sensitivity of warm rain initiation to radiation is consistent with the warm cloud observations of the Tropical Rainfall Measuring Mission (TRMM) satellite (Liu & Zipser, 2009, ) and the Rain In shallow Cumulus over the Ocean (RICO) campaign (Small & Chuang, 2008, ).

Plain Language Summary Anthropogenic aerosol effects on water clouds cause an indirect cloud-albedo effect, which is one of the largest uncertainties in climate modeling (Intergovernmental Panel on Climate Change, 2014, ). Such uncertainty relies on a foundational question in cloud physics: Why do water clouds rain so quickly (in 30min or less)? In this study, a numerical model is developed to show how radiation accelerates rain initiation, providing a potentiality for climate models to better represent water clouds.