FACTOID # 13: New York has America's lowest percentage of residents who are veterans.

 Home Encyclopedia Statistics States A-Z Flags Maps FAQ About

 WHAT'S NEW RELATED ARTICLES People who viewed "Ceilometer" also viewed:

SEARCH ALL

Search encyclopedia, statistics and forums:

(* = Graphable)

Encyclopedia > Ceilometer
Laser Ceilometer

A ceilometer is a device that uses a laser or other light source to determine the height of a cloud base. Ceilometers can also be used to measure the aerosol concentration within the atmosphere such as particulate matter. Image File history File links Ceilometer. ... Image File history File links Ceilometer. ... For other uses, see Laser (disambiguation). ... This article refers to meterology, for the airborne base of Captain Scarlet see Cloudbase. ...

• An optical drum ceilometer uses triangulation to determine the height of a spot of light projected onto the base of the cloud. It consists essentially of a rotating projector, a detector, and a recorder. The projector emits an intense beam of light above into the sky at an angle that varies with the rotation. The detector, which is located at a fixed distance from the projector, uses a photoelectric cell pointing vertically. When it detects the projected light return from the cloud base, the instrument note the angle and the calculation gives the height of clouds.

Triangulation can be used to find the distance from the shore to the ship. ... For other uses, see Cloud (disambiguation). ... A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ...

## Laser Ceilometer

• A laser ceilometer consist of a vertically pointing laser and a receiver in the same location. It determines the height by measuring the time (δt) required for a pulse of light to be scattered back from aerosols within the atmosphere.
where c is the light speed in the air.

Generally, the size of the particles in question are similar in size to the wavelength of the laser. This situation leads to MIE theory. Mie theory, also called Lorenz-Mie theory or Lorenz-Mie-Debye theory, is a complete analytical solution of Maxwells equations for the scattering of electromagnetic radiation by spherical particles (also called Mie scattering). ...

For cloud base determination purpose, due to the ceilometers ability to pick up any particle in the air (dust, precipitation, smoke, etc...), it will give occasional false readings. As an example, depending on the threshold used, falling Diamond dust (Ice Crystals) may cause the ceilometer to report a cloud height of zero, even though the sky is clear. Diamond dust is the name commonly used to refer to a ground-level cloud composed of tiny ice crystals. ...

Using these last properties, ceilometers will have other uses. Since the instrument will note any returns, it is possible to locate any faint layer where it occurs, additionally to the cloud's base, by looking at the whole pattern of returned energy. Furthermore, the rate at which diffusion happens can be noted by the diminishing part returned to the ceilometer in clear air, giving the coefficient of extinction of the light signal. Using these data could give the vertical visibility and the possible concentration of air pollutants. This has been developed in research and could be applied for operational purpose. Air pollution Pollution is the introduction of pollutants (whether chemical substances, or energy such as noise, heat, or light) into the environment to such a point that its effects become harmful to human health, other living organisms, or the environment. ...

Results from FactBites:

 Chilbolton Observatory (105 words) Scientists use the ceilometer to measure the sizes of precipitation particle and to discover whether a cloud colder than zero degrees is made up of ice or water. The latest results from the ceilometer can be found on the Chilbolton Weather Web. To see measurements taken with the IR lidar ceilometer look in the research section of the site.
More results at FactBites »

Share your thoughts, questions and commentary here