Classification of Snow Flakes and their Structures

Many snow flakes were photographed between 1951 and 1954 in Japan, and they were classified, according to the purposes by three methods, their metamorphic stages, shapes in falling state, and crystal habits. It was observed that the snow flakes change their crystal states in the process similar to that of the fallen snow. Considering aerodynamically the shape and velocity of snow flakes in falling state, a clue for presuming the uniformity of crystal habit in snow flakes was acquired. In the photographs of snow flakes obtained hitherto, it was found that in all types of snow crystals is formed one snow flake with the same type only, while another with almost all combinations between the different types is formed. All the ways of contact geometrically possible, namely, point, line, intertwined, and irregular contact were found in the snow flakes. The top of branch of dendritic crystals plays a leading role in the adhesion mechanism between the crystals. From those results, it was presumed that the large snow flakes might be composed of snow crystals of dendritic type