The electrification of ice and water at temperatures around the freezing point

Abstract

An attempt has been made to see whether there is a basic charge separation process which operates between ice and water when they are moving relative to one another. Measurements have also been made on the potential differences produced between ice and water under a variety of different conditions and the effect on the potential differences of having air bubbles within the ice/water interface has been studied. Apparatus is described for the measurement of the electrical effects on freezing and melting bulk samples of water. No evidence has been found for a charge separation process which operates only when water moves relative to ice at the freezing point However, the results show that at freezing rates of 10 µm s(^-1) and above that the mechanism proposed by Workman and Reynolds (1950) is responsible for the majority of the net charge separated, whereas, at very low freezing rates or on melting, the Temperature Gradient Mechanism, proposed by Latham and Mason(1961) predominates. The relevance of the electrification of ice and water to the origin of electrical charges in clouds is discussed, and explanations of the results of earlier work on simulations of conditions in clouds are put forward, in the light of the results obtained during the experiments with bulk water samples.