Clouds are ubiquitously turbulent. The cauliflower-like appearance of cumuli and the shakes and bumps of a plane as you descend through a cloud layer for landing are testaments to the differential motion of air on a macroscopic scale. But does it matter at the scale of a cloud droplet or ice crystal? Are cloud droplets bigger or smaller as a result of fluctuations in the scalar fields caused by turbulence? Do more or fewer aerosol particles become cloud droplets in a turbulent environment?
Questions like these have motivated much of the research in Michigan Tech’s cloud chamber, called the Pi Chamber because of the 3.14 cubic meter volume. The chamber is a Rayleigh-Bénard convection cell; we can create and hold a steady-state mixing cloud in the chamber for tens of hours at a time. I will address aspects of cloud formation, cloud glaciation, and cloud dissipation that we have investigated in the chamber that highlight the interactions among aerosol, clouds, and turbulence.
Will Cantrell studied atmospheric science at the University of Alaska Fairbanks, receiving his Ph.D. in 1999, having participated in nine field campaigns as a graduate student. As a postdoctoral scholar at Indiana and as a faculty member at Michigan Technological University (MTU), he has spent most of his time in the lab. He is currently one of the principal investigators for the Pi Chamber at MTU, is involved in an effort to design (and perhaps build) a larger convection chamber which will enable observation of the transition between condensational growth of cloud droplets to collision-coalescence, and is a member of a team designing a chamber to study of clouds on other planets. Sometimes, in summer, you can find Will roll casting to rising trout on the Otter River, near Houghton.