On the Ice-nucleating Ability of Rock-forming Minerals and Soil Particles&lowast

Abstract

The ice-nucleating abilities of various rock-forming minerals which exist commonly on the surface of the earth were determined in laboratory. The most effective minerals as ice nuclei among the minerals tested are magnetite, hypersthene, kaolinite and sanidine. Quartz, amphibole, olivine, calcite and orthoclase are found to be less effective. As for the volcanic ejecta, the degree of weathering to which they have been subjected seems to give significant effect on their ice-nucleating abilities.
The temperature spectra of atmospheric ice nuclei observed in Tokyo were compared with those of materials which were considered to have arrived in the air over Tokyo, and fair agreements were seen between them.
It is suspected that meteoritic dust particles which contain magnetite or minerals similar to it might act as effective ice nuclei.