On the Shape and Movement of Cirrus Uncinus Clouds by the Trigonometric Method utilizing Stereophotographs

Studies of Cirrus Clouds: Part II

Abstract

Cirrus uncinus clouds were observed by stereophotographs, and were analysed by means of the trigonometric method.
It was confirmed, as a result, that the trail of the cloud had a spatial structure, and that the velocity of the movement of the cap of the cirrus uncinus cloud and the end of its trail coincided with the wind velocity at the respective level. From this fact it was explained that the cloud extended and rotated on a horizontal plane. Namely, the cloud showed the tendency for the trail of the cloud to approach in direction parallel to the prevailing vertical wind shear.