Abstract
There is a phenomenon called “kasumi” in Japan, which appears mainly in Spring and makes atmosphere opaque. The general feature of this phenomenon is that objects at distance-say one, two or more miles gradually become hidden from the sight as the day advances. Objects near horizon become usually invisible but not those with greater height such as mountain tops. In Japanese picture of “kasumi” are often represented cherry trees in full blossoms hidden, however, by kasumi at their middle branches, exposing their trunks and top parts. Kasumi has a tint very thin and somewhat bluish. It always extends horizontally like a sheet of evening smoke, but on approaching it, no body has ever perceived any material particles floating there, as it is the cases in smoke, haze or mist. It is something like optical turbidity, an allied phenomenon of scintillation and mirage, but hitherto there has been no research on this direction. Only a vague idea that it might be a product of very fine particles of water in air is generally prevailing.
The author wishes to define the phenomenon scientifically by fixing up the conviction of “kasumi” taking old Japanese verses into consideration, which refer the phenomenon. He collected 72 ‘Utas’. By adding his own observations, he drew conclusion from these verses that “kasumi” is the phenomenon appearing most in Spring, seldom in winter and Autumn, and most seldom in Summer. It Sometimes settles over along river and sometimes emigrates along coastal line, mostly encircle_??_ hills round its slope. The height at which kasumi is stratifying is from 10 m to 200 m above the ground. The author left the problem on the physical nature of “kasumi” to future investigation. (Fujiwhara)
