CEE Seminar: How Turbulence Influences Cloud Optical Properties and Precipitation: Laboratory Studies of Turbulent Moist Rayleigh-Benard Convection

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.