Summary
Experimental work was conducted in an igloo, half way up Mt. Taisetsu (1050 m), Mt. Tokachi (1030 m) and Mt. Okuteine (820 m) in Hokkaido. One solid nucleus (center nucleus) was observed almost always in the central portion of a snow crystal. From their electron micro-diffraction patterns, the materials of the nuclei were classified into three kinds; a single crystal, polycrystalline or amorphous substances. The patterns of the single crystal gave a hexagonal cross grating, the atomic arrangement in their basal plane had some similarity to that of an ice crystal. Some polycrystalline center nuclei were small sea salt, particles. Their shape was similar to that of the nuclei of sea sprays, and their patterns coincide with that of the sea salt. Some amorphous center nuclei were observed which looked like a liquid droplet under the operating condition of the electron-microscope. It seemed that they are chemical components in the sea salt such as KCl or MgCl particles.
In the other parts of snow crystal, many smaller nuclei (condensation nuclei) were observed. These nuclei are also aerosols in the atmosphere; their size was 0.1∼0.01 μ in diameter. They gave the Debye-Scherrer ring; their patterns were different in each specimen. Their materials consist of various substances. From these data, the origin of nuclei and the mode of action of center nucleus were discussed.
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Kumai, M. Electron-microscope study of snow crystal nuclei: II. Geofisica Pura e Applicata 36, 169–181 (1957). https://doi.org/10.1007/BF01993006
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DOI: https://doi.org/10.1007/BF01993006