HOPKINS GLOSSARY OF WEATHER TERMS C
- The height above the surface of the base of the lowest layer
of clouds that obscures more than half the sky; reported for only
broken and overcast sky cover. The ceiling may be estimated by
visual means or measured by a ceilometer.
- An automatic, recording, cloud-height indicator. A light
beam is projected upward on to the cloud base; the reflected light
is detected by a photocell and the height is determined by triangulation.
- A rotation-type anemometer consists of an array of
three (or four) hemispherical cups mounted symmetrically about
a vertical rotation axis. The rate of rotation of the cup array
is a measure of the wind speed, as determined indirectly
by gearing a mechanical or electrical counter to the shaft.
Last update 6 June 1996
Edward J. Hopkins, Ph.D.
Department of Atmospheric and Oceanic Sciences
University of Wisconsin-Madison