CEE Seminar: How Turbulence Influences Cloud Optical Properties and Precipitation: Laboratory Studies of Turbulent Moist Rayleigh-Benard Convection
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February 27, 2018 - 12:00pm to 1:00pm
Raymond A. Shaw, Professor, Michigan Technological University, Atmospheric Sciences Program and Department of Physics
Aerosol particles, such as sea salt, dust and anthropogenic pollution, influence the optical properties of clouds and the tendency of a cloud to form precipitation through droplet collisions. We have investigated cloud droplet growth in a turbulent environment under varying levels of aerosol concentration. The results reveal a surprising role of turbulence in cloud droplet growth that leads to two regimes: a polluted cloud regime in which thermodynamic conditions are rather uniform and cloud droplet sizes are similar, and a clean cloud regime in which thermodynamic conditions are highly variable and cloud droplet sizes are very diverse. The narrowing of droplet size range under polluted conditions introduces a new stabilizing factor by which increased aerosol concentration can suppress precipitation and enhance cloud brightness.