Bergeron process

The Wegener–Bergeron–Findeisen process (after Alfred Wegener, Tor Bergeron and W. Findeisen), (or “cold-rain process”) is a process of ice crystal growth that occurs in mixed phase clouds (containing a mixture of supercooled water and ice) in regions where the ambient vapor pressure falls between the saturation vapor pressure over water and the lower saturation vapor pressure over ice.