- 行业: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
Any of a class of instruments for sizing and counting large numbers of individual aerosols or hydrometeors to characterize populations, or also for imaging and classifying the shapes of individual hydrometeors by measuring the optical illumination, scattering, or attenuation of a laser beam by each particle and recording the result electronically. Included are optical scattering probes and optical imaging probes. Primarily airborne instruments, they can be adapted for stationary use at the surface for precipitation or fog monitoring, in some cases with forced ventilation to create a particle flux.
Industry:Weather
A rarely used term describing any of the phenomena of meteorological optics, such as a halo, rainbow, or mirage.
Industry:Weather
The vertical integral of the density of absorbers between two altitudes; used mainly in determining the transmission through an absorbing gas. Dimensions are mass per unit area (e.g., kg m<sup>−2</sup>).
Industry:Weather
An optical particle probe that records the size and shape of the shadow of each particle that intercepts and attenuates the illumination by a laser beam. Of these, shadowing probes differentiate particle shadows from the light of the unobstructed beam with linear arrays of optically activated diodes; for example, the one-dimensional cloud probe normally for sizing 10-μm to either 300- or 600-μm cloud hydrometeors, the two-dimensional cloud probe normally for sizing and imaging 25–800-μm cloud hydrometeors, and the two-dimensional precipitation probe normally for sizing and imaging 200-μm to 6. 4-mm precipitation hydrometeors. The electronics record either the maximum one-dimensional width of the shadow or two dimensions and shape of the shadow, to estimate particle size and type (raindrop, crystal growth habit, etc. ). Another type, the cloud particle imager, illuminates each particle with a pulsed laser and records size, shape, and detailed structure of each hydrometeor with a high-resolution solid-state digital imaging camera, normally to size 5-μm–2. 3-mm hydrometeors.
Industry:Weather
Same as spectral hygrometer; a group of hygrometers based on the spectral attenuation of radiation by specific water vapor absorption lines or bands.
Industry:Weather
The optical thickness measured vertically above some given altitude. Optical depth is dimensionless and may be used to specify many different radiative characteristics of the atmosphere. See aerosol optical depth, cloud optical depth, Rayleigh optical depth.
Industry:Weather
Device for counting the concentration of particles in air that takes advantage of the light scattering caused by particles. Modern instruments use laser light sources and are able to give information on the shape of the particle or its physical state.
Industry:Weather
A measure of the length of the path through the atmosphere to sea level traversed by light rays from a celestial body, expressed as a multiple of the pathlength for a light source at the zenith. It is approximately equal to the secant of the zenith distance of the given celestial body for zenith distances up to about 70°. Bemporad's formula must be used for more accurate determination. To get a representative value at high elevation, the above values must be multiplied by the ratio of the actual atmospheric pressure to the sea level pressure.
Industry:Weather
In astronomy, the arrangement of the earth, sun, and one of the other planets or the moon, in which the angle subtended at the earth between the sun and the third body, in the plane of the ecliptic, is 180°. When this is the case, a superior planet is on the opposite side of the earth from the sun and is most easily observed. Compare conjunction, quadrature.
Industry:Weather
The limiting values of ceiling, visibility and wind, or runway visual range, established as safety minimums for aircraft landings and takeoffs. Civil aircraft operate under limits stated in Civil Air Regulations and military aircraft operate under limits established by the respective military organizations. Limits for day and night operations usually differ. Also, the limits vary according to airport environment, navigational aids, and type of aircraft.
Industry:Weather
