Symposium on Ice Crystals and Ice Nucleation, Berkeley, California, August 1963

Abstract

Experiments have shown that ice can adhere to ice at temperatures down to -30° C and that plate-like ice crystals have greater adhesive powers than columnar ones. The contention that these observations provide evidence in favour of the `liquid film' hypothesis appears disputable. It has also been shown that `spongy ice' is formed at ambient temperatures below -4.5° C and can contain up to 85% liquid water trapped in a mesh of interlocking ice dendrites. The growth of spongy ice may have an inhibitory effect on the Workman-Reynolds mechanism of thunderstorm electrification. A rival theory is described which is based on charge transfer associated with temperature gradients in ice. The conclusion drawn from the Symposium is that although much information on the properties of ice has recently been acquired the important problems remain unsolved.