Dear All,

Next week (Nov 21, at 1:15 pm), we will host prof. Wojciech Grabowski (NCAR / Univ. Warsaw) for the AGH Environmental Physics Group seminar.

The talk will take place in lecture hall C ("pink"), building D-10, 3rd floor (address: Reymonta 19).

Title: Growth of Cloud Droplets in a Turbulent Environment

Abstract: Formation of precipitation in warm (ice-free) clouds involves both diffusional and collisional growth of cloud droplets. For both, cloud turbulence has been argued to play an important role. In this talk, I will review recent research in this area focusing on droplet diffusional growth in adiabatic (i.e., undiluted) cloud volumes. The focus on such regions is justified by observations and numerical modeling that show rain and drizzle formation typically taking place in undiluted and weakly diluted cloud volumes. At the same time, however, in-situ aircraft observations show that droplet spectra in such regions are often significantly wider than predicted by a simple adiabatic parcel ascent from the cloud base. Droplet spectral width is important for the onset of droplet gravitational collisions as well as for the transfer of solar radiation through clouds. The problem of spectral broadening due to cloud turbulence attracted significant attention of cloud physics and turbulence communities over the last couple decades. Theory and numerical simulations using idealized frameworks of stochastic models, direct numerical simulation (DNS), and scaled-up DNS have all been used to explain spectral broadening observed in natural clouds. Simple concepts related to the impact of turbulence on the diffusional growth of cloud droplets together with results of numerical simulations will be presented.

Speaker: Prof. Wojciech W. Grabowski National Center for Atmospheric Research (NCAR), Boulder, CO, USA Institute of Geophysics, Faculty of Physics, University of Warsaw https://scholar.google.com/citations?user=WVjmW3wAAAAJ

ZFŚ seminar site & mailing list: https://zfs.agh.edu.pl/en/seminars

Best regards, Sylwester Arabas