DROPLET FEEDBACK ON VAPOR IN A WARM CLOUD

A new model to study the effect of turbulence on the cloud droplets in the condensation phase is proposed and its behavior investigated by direct numerical simulations. The model is a generalization of the one by Celani, Mazzino, Tizzi, New J. Phys. 10, 075021 (2008), where the droplet feedback on vapor is now explicitly taken into account. Physically, it amounts to considering the fact that when a cloud droplet increases its size, vapor is subtracted from the ambient with the net result of a local reduction in the supersaturation field. It is shown how this effect plays to reduce the broadening of droplet size spectra in the condensation stage and thus to produce results in closer agreement with observations.