Nephoscope

Nephoskop (Greek nephele, nephos; fog, cloud), also clouds or clouds mirror diameter called, is an instrument for measuring the direction and apparent velocity of the cloud movements.

Description

The clouds mirror consists of an ordinary and a black, rear butted mirror with incised compass. Most of the black mirror is used, the light only at very dimly lit clouds. Before each observation, the mirror is placed horizontally so that " N" is directed to the north.

The observer turns so that he sees in the small central circle a characteristic point of the cloud and observed, to which side moves toward the cloud image. The direction of the opposite indicates the direction from which the clouds come. Then one determines the time in which the selected point cloud travels a known distance in the mirror, such as the 2 cm long way from a circle to the next. The desired angular velocity is then equal to the length of the path that the mirror image was made ​​, divided by the product of the number of seconds that were required for this path, and the perpendicular distance of the eye from the mirror.

History

The clouds mirror was invented in 1845 by Aimé. However, the designation Nephoscop goes back to the physics teacher Carl Braun, who in 1865 constructed a similar instrument.