The nucleation behavior of supercooled water vapor in helium

Abstract
The nucleation behavior of supersaturated water vapor in helium is experimentally investigated in the temperature range of 200–240 K. The experiments are performed using a pulse expansion wave tube. The experimental results show a sharp transition in the nucleation rates at 207 K. We suggest that the transition is due to the transition of vapor/liquid to vapor/solid nucleation (ordered with decreasing temperature). A qualitative theoretical explanation is given based on the classical nucleation theory and the surface energy of ice.