Viewed from afar, clouds can look like floating, wispy puffs of cotton. Up close, micrometer- to millimeter-sized droplets of liquid water are buffeted by turbulent winds as dry air surrounding a cloud mixes with the moisture-laden air inside. The continually morphing shapes of clouds are visible manifestations of that turbulent mixing.
Cloud physicists have long wanted to know how turbulent mixing affects the size and spatial distribution of cloud droplets at centimeter or smaller length scales. Those are the scales at which the droplets collide and merge, evaporate, and interact with aerosols. Such microphysical processes profoundly shape large-scale cloud properties, among them the likelihood of producing rain and other precipitation and their ability to reflect incoming sunlight back into space.
To get a definitive three-dimensional picture of cloud structure at the scale of a few cubic centimeters, Raymond Shaw of Michigan Technological University, Jacob Fugal of the Max Planck Institute...
