Charge separation associated with frost growth

Abstract

Abstract Observations have shown that negatively charged ice fragments are ejected from ice surfaces growing by water vapour deposition. Laboratory experiments with exaggerated temperature and vapour gradients were performed to quantify the charge transfer and its dependence on temperature and water vapour density. It was found that the temperature of the growing ice plays a strong role in determining the rate of charge transfer, with a pronounced maximum in the range −15 °C to −25 °C, but the growth history of the ice surface is also shown to be important. The temperature and vapour gradients employed in the study are unrepresentative of those encountered in the atmosphere, but the underlying physics of this phenomenon may be applicable to phenomena that do operate in thunderclouds. The physical processes responsible for the charge transfer remain unidentified.