- 업종: 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, ...
A technique for making winds-aloft observations in which two theodolites located at either end of a base line follow the ascent of a pilot balloon. Synchronous measurements of the elevation and azimuth angles of the balloon, taken at periodic time intervals, permit computation of the wind speed and wind direction as a function of height.
Industry:Weather
An arithmetic plot of the accumulated values of observations of two variables that are paired in time and thought to be related. As long as the relationship remains constant, the double-mass curve will appear as a straight line; a deviation denotes the timing of a change.
Industry:Weather
In hydrometeorology, a test of “the consistency of the rainfall record at a given station by comparing its accumulated annual record with that of the accumulated annual, or seasonal, mean values of several other nearby stations. ”
Industry:Weather
A double-headed tide with a high water consisting of two maxima of similar height separated by a small depression (double high water), or a low water consisting of two minima separated by a small elevation (double low water). Examples occur at Southampton, England, along the coast of the Netherlands, and off Cape Cod, Massachusetts.
Industry:Weather
1. On the surface of a substance, a layer of electric dipoles, the axes of which have an average orientation normal to the surface. Double layers may appear on interfaces of solid and gas, liquid and gas, liquid and liquid, etc. They arise whenever media with different electron affinities (forces of attraction or work function) are contiguous, and dipoles are available. A net potential difference, the electrokinetic potential exists across a double layer. 2. See electric double layer.
Industry:Weather
Nearly synonymous with birefringence but may be applied in a restricted sense to transparent (at visible frequencies) media with sufficient birefringence that images seen through them are split. The term originates from the Danish physician Erasmus Bartholinus, who in 1669 wrote about what he observed through the crystalline solid calcite: “objects which are looked at through the crystal do not show, as in the case of other transparent bodies, a single refracted image, but they appear double. ”
Industry:Weather
Fluid motion that results from the release of potential energy from one of two or more factors that determine the density of a fluid (for example, heat and salinity). Even if the density is statically stable, convection may result if one of the factors is statically unstable. There are three major types of double diffusive convection relevant to heat and mass transport in the ocean. 1) Finger modes may occur when hot salty fluid overlays cold fresh fluid so that convection results in the form of narrow cells (salt fingers) carrying salty water downward and freshwater upward. 2) Diffusive modes occur when a stable salinity field is heated from below so that convection results in the form of a series of well mixed layers separated by sharp density gradients. 3) Intrusive modes occur when there are horizontal density gradients in one of the components determining the density of the fluid even if the fluid density as a whole is horizontally uniform. This instability develops in the form of interleaving intrusions.
Industry:Weather
1. An instrument for measuring the ultraviolet in solar and sky radiation. 2. A device, worn by persons working around radioactive material, that indicates the dose of radiation to which they have been exposed.
Industry:Weather
In general, the width of the Doppler spectrum, measured in units of either frequency or velocity. Quantitatively, the Doppler spread is usually defined as the standard deviation of the Doppler velocity about its mean value, regarding the velocity as a continuously distributed random variable with a probability density function equal to the normalized Doppler spectrum. See Doppler spectral moments; Doppler spectral broadening.
Industry:Weather
Increase in the Doppler spread arising from different processes or phenomena. The Doppler spectrum is ordinarily regarded as a reflectivity-weighted distribution of the radial velocities of the scatterers in the pulse volume. A spread of radial velocities exists because of turbulence and wind shear in the pulse volume and, for precipitation targets, because the particles have a range of fall velocities. The spectrum may be further broadened by processes that have little to do with the radial velocity distribution of the scattering elements. These processes include 1) the cross-beam wind velocity, which induces a broadening proportional to the beamwidth because of the radial component of the cross-beam wind vector pointing in directions away from the beam axis; 2) uncertainties in the measurement of the Doppler spectrum because of statistical fluctuations in the spectral estimates that arise from short sampling times; and 3) motion of the radar beam relative to the targets as a result of scanning in azimuth or elevation, which further reduces the sampling times.
Industry:Weather
