Abstract
Cirrus clouds were observed by stereophotogrammetric methods at Sapporo, Hokkaido, from August to October in 1964 and 1965. From the analytical results of the environmental situation near the cirrus cloud level, the following significant facts were found.
The cirrus clouds were observed in a layer with the dry adiabatic lapse rate and vertical wind shear. In the case of the cirrus uncinus clouds, remarkably stable layers existed above and below the cloud and the trail of the cloud was in the stable layer below. In the case of cirrus fiblatus cloud and cirrus spissatus cloud, the layer above was stable but the layer below was not quite stable and had a nearly dry adiabatic lapse rate. It was noted that the static stability in the lower part of cirrus clouds was important to explain the characteristic shape of the cirrus clouds.
From the resutls, a useful information was obtained to decide the height of a cirrus cloudeven if it is one point observation.
