Measurements of Snow Crystal Growth Dynamics in a Free-fall Convection   Chamber
  We present a series of experiments investigating the growth of ice crystals from water vapor in the presence of a background gas. We measured growth dynamics at temperatures ranging from -2 C to -25 C, at supersaturations between 0.5 and 30 percent, and with background gases of nitrogen, argon, and air at a pressure of one bar. We compared our data with numerical models of diffusion-limited growth based on cellular automata to extract surface growth parameters at different temperatures and supersaturations. These data represent a first step toward obtaining precision ice growth measurements as a function of temperature, supersaturation, background gas pressure and gas constituents.   From these investigations we hope to better understand the surface molecular dynamics that determine crystal growth rates and growth morphologies. 
Kenneth G. Libbrecht, Helen C. Morrison, and Benjamin Faber