Since Assmann's observation of “Rauhreif” on Mt. Brocken and Pernter's proposition of “Rauhreif” and “Rauhfrost” many years elapsed. Still the opinions of various investigators on the classification of rime are not in concordance. From his own observations and others, the author remarks firstly, like Pernter and others, that there are two processes in formation of rime: sublimation and freezing, by which the crystallised and amorphous structures of rime are produced respectively. And secondly he concludes that there are the third prqcess, con bination of sublimation and freezing, by which numerous different intermediate forms of rime are produced, In the course of variation of atmospheric conditions, especially of wind, temperature and moisture, the two processes take place intermittently and alternately. The intermediate and generally complicated forms of rime in calm fogy morning are produced in this way. Thus we would propose the following subdivisions of rime:-
1. Crystallized form by sublimation (without fog of water droplets.)
2. Amorphous form by freezing 'with fog of supercooled water droplets)
3. Intermediate or combined form
by combination of the two processes.
In addition, the author propos_??_s to apply the same principle of classification to the other forms of solid hydrometeors, snow, hail and graupel, and others.
