Observations of the Ice-Nucleating Temperature of Some Chemical Substances

[摘要] In order to get a clue to the relation among the ice-nucleating activity of substances and their crystal structure, solubility and other properties, a thermostat-like cold-chamber functioning at any temperature higher than -20°C has been constructed and about 30 materials-oxides of cobalt, nickel, cadmium, magnesium and zinc, halides of alkali and alkalineearth metals and of silver, lead, and besides, cadmium sulfide, magnesium telluride, etc.belonging to either the cubic or hexagonal system have been examined as to the temperature of ice crystal formation.The main findings are described as follows:1) The more closely the lattice constant approximates to that of ice and the more definite the insolubleness in water is, the more likely the substances, both cubic and hexagonal, are to exhibit marked ice-forming property.2) Lead iodide and silver iodide are the most effective of the substances examined, the ice crystals being found to form from supercooled clouds at -2.3° and -2.9°C, respectively, in the presence of these foreign nuclei.

[学科分类] 大气科学