[PAOCQ] Raymond A. Shaw (Michigan Technological University)

This week’s talk is being held virtually.

“Making it rain: Designing a convection-cloud chamber for exploring interactions between aerosols, clouds and precipitation”

Clouds are collections of droplets and ice crystals, formed on aerosol particles, all interacting within a turbulent environment. Understanding these interactions is central to current challenges ranging from the influence of clouds on climate, to solar radiation management strategies like marine cloud brightening. Turning to the laboratory is one way to make progress because we control or characterize all initial and boundary conditions. In the “Pi convection-cloud chamber”, a pi-cubic-meter turbulent cloud is generated by feeding aerosols into a water-supersaturated environment created by moist Rayleigh-Benard convection. All microphysical processes that are usually considered “sub-grid-scale” even in detailed models, are fully represented. The resulting cloud microphysical and optical properties are similar to those observed in stratocumulus, and over the last decade the Pi chamber has provided insight into the role of turbulence on cloud droplet activation and growth, the formation of persistent mixed-phase clouds, and the cloud dispersion indirect effect. Now, the ACDC2 consortium has been developing a design for a much larger convection-cloud chamber that will allow droplet growth by collision-coalescence in addition to growth by condensation. That capability will allow interactions within a fully-coupled aerosol-cloud-precipitation system to be explored and directly compared to detailed models. We envision that this would exist as a national user facility available to the atmospheric research community for advancing our understanding of cloud processes relevant key uncertainties in weather and climate models.

PAOC Colloquium

Interdisciplinary seminar series that brings together the whole PAOC (Program in Atmospheres, Oceans, and Climate) community. Seminar topics include all research concerning the physics, chemistry, and biology of the atmospheres, oceans and climate, as well as talks about societal impacts of climatic processes.

Contact:  paoc-colloquium-comm@mit.edu