Asahikawa city in Hokkaido in winter has very low temperature despite its situation in the middle latitude zone, and frequent ground inversion, since it is located in the inland.
The area of pulp mills in the northeast of the city and its neighborhood is covered every norning in winter by thick smog which consits of smoke and steam originated from those mills.
There are sometimes obrerved falls, of considerable intensity, of snow from the somog layer, which is named by A-Yamamoto “Factory Snow”.
The present paper gives the record of the Factory Snow observed during 1967 through 1970.
Though the crystal of th Factory Snow is found essentially the same as that formed through the process of the Nakaya's diagram, its formation process should of course be different.
The investigation on the formation of the Factory Snow in future will be of some help for development of cloud physics, because the formation is considered to be made under the intermediate condition between natural process and laboratory process.