Abstract
In winter, early in the morning, there was sometimes observed a low cloud layer near the coast of Ishikari Bay, Hokkaido. Still and motion pictures of this type of cloud layer were taken from the top of Mt. Teine. The results indicate that these clouds seem to have been caused by the mixing of relatively warm air over the bay and cold air flowing out from the Ishikari Plain. These "coastal clouds" occurred only on a clear morning which follows a clear night, and they were found only over the coast of the bay. The observed clouds were small in scale, and it did not produce precipitation. It is expected, however, that such clouds may occur on a larger scale in other places, and that it may produce precipitation even if there is no front nor mountain.
