ceilometer


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ceilometer

(sēlŏm`ĭtər), in aviation and meteorology, automatic instrument used to record ceiling, i.e., the altitude of the lowest cloud layer covering more than half of the sky. The ceilometer consists essentially of a projector, a detector, and a recorder. The projector emits an intense beam of light into the sky. The detector, located at a fixed distance from the projector, uses a photoelectric cell to detect the projected light when it is reflected from clouds. In the fixed-beam ceilometer, the light is beamed vertically into the sky by the projector and the detector is aligned at various angles to intercept the reflected light; in the rotating-beam ceilometer, the detector is positioned vertically and the light projected at various angles. In either case, trigonometry is used to determine the altitude of the clouds reflecting the light from a knowledge of the angle at which the light is detected and the distance between the projector and detector. The recorder is calibrated to indicate cloud height directly. False readings from extraneous light sources are reduced by modulating the projected light beam so that it can be recognized when it is reflected.

ceilometer

[sē′läm·əd·ər]
(engineering)
An automatic-recording cloud-height indicator.

ceilometer

ceilometer
Cloud ceilometer.
An instrument to measure the heights of clouds during the day. The ceilometer beams a light at the cloud base, which it detects by a photoelectric cell. A process of triangulation then determines the height of the cloud.
References in periodicals archive ?
Laser beam ceilometer readouts are still the primary source of data, but observers must go outside to assess the entire sky and see whether the ceilometer readout represents the actual ceiling or not.
The Meteorology System shall at least consist of the following units: 2 combined wind speed and wind direction sensors, 1 air pressure sensor, 1 combined air humidity and air temperature sensor, 1 ceilometer, two wind speed and wind direction displays, one meteorology display (displaying QNH, QFE, dew point, air humidity and air pressure), 1 cloud height display and 1 combined datalogger and data distribution unit.
com)-- Lufft left no stone unturned, to fulfill all requirements of the recent ceilometer tender of the Dutch royal weather service KNMI.
For example, the AWOS/ASOS ceilometer looks at the sky from one location near the touchdown zone during "detection cycles" that can each be as brief as 12 seconds (during which thousands of pulses are sent) and averages these over 30 minutes, with a double-weighted average over the last 10.
pulse to be scattered from the cloud and returned to the ceilometer
Tenders are invited for Supply And Installation Of Ceilometer - Qty 01 Set
Earlier, the DWD had already opted for the cloud ceilometer from the Fellbach-based company.
If the ceilometer says the ceiling is 700 feet, though, you may have ground contact but whether you can see anything over the nose depends on the density of the clouds.