Observations of an Impurity-driven Hysteresis Behavior in Ice Crystal   Growth at Low Pressure
  We describe observations of a novel hysteresis behavior in the growth of ice crystals under near-vacuum conditions. Above a threshold supersaturation, we find that the ice growth rate often exhibits a sudden increase that we attribute to an impurity-driven growth instability. We examine possible mechanisms for this instability, which can be used to produce clean, faceted ice surfaces. 
Kenneth G. Libbrecht