Abstract
Using the shadow photograph method reported in a previous paper3), size distribution of various kinds of snow crystals and snow flakes were measured. Observations were carried out at spots half way up Mt. Taisetsu and Mt. Tokachi, both 1050m above sea level, in winter of 1953-54. Fig. 1 shows size distribution for various types of single snow crystals, which were obtained within a comparatively short time of snow fall. These results were compared with those of Nakaya and Sekido, observed during the whole winter season of 1933-35. Table 1 shows that there is good coincidence among them in respect of the most probable size and range of size for crystal forms of column, simple plate and powder snow. But size and size-range differ for needle and plane dendritic crystal forms.
The axis ratios of columnar crystals with the skeleton-shaped form were measured. As shown in Table 3, the average length of principal axis is 0.84mm, and the mean axis ratio is 2.48. Combining this result to those measured from the microphotographs, obtained by Nakaya and others, it is found that the value of axis ratio increases in proportion to the length of principal axis, as shown in Fig. 2.
By taking photographs of snow flakes after separating into single crystals, the size distribution of snow-flake-forming crystals was measured. Table 4 represents the data obtained from the records of such snow flakes.
Snow flake consisting of two crystals was investigated quantitatively. From the results, the author proposed to classify them into the following two types. One is the type in which resemblance to each other in form and size is observed for two crystals forming a snow flake. The other type is otherwise. Concerning the former, the probability of coagulation is calculated from the data of observation. It seems that its inclination is similiar to the coagulation of colloid particles of various sizes.
