Written by: Larry D Frost July 15, 2014 Dr. Sarma Rani received a NSF grant in the amount of $173,000 for his collaborative research effort between the University of Alabama in Huntsville and Cornell University on the role of microphysical processes and turbulence intermittency in droplet coalescence in warm cumulus clouds. This study addresses two central outstanding questions in the current understanding of warm rain production. They concern the mechanisms leading to the formation of fast-growing "statistically fortunate" drops, and to the broadening of the cloud droplet spectrum toward larger drop sizes, both of which hasten the "colloidal instability" of the cloud, resulting in precipitation. The objective of this study is to perform a multiscale, coupled computational-stochastic investigation of the role of turbulence in droplet coalescence and growth in realistic, high-Reynolds-number cloud turbulence.
