- 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, ...
A vacuum tube consisting essentially of an electron gun producing a concentrated electron beam that impinges on a phosphorescent coating on the back of a viewing face or screen. The excitation of the phosphor produces light, the intensity of which is controlled by regulating the flow of electrons. Deflection of the beam is achieved either electromagnetically by currents in coils around the tube or electrostatically by voltages on internal deflection plates.
Industry:Weather
Bright features that move outward through the solar corona. These large expulsions of magnetized plasma often extend more than 90° along the solar limb and move with velocities ranging from 10 to 2000 km s−1. These events disturb the solar wind, which in turn affects the earth's magnetosphere, causing magnetic storms and other disruptive events.
Industry:Weather
A mapping of a pixel value to a color value shown on a display device. Typically, a CLUT will map the input into a color presentation, but if all colors are of equal intensity for each input value, then a gray scale or black-and-white image results.
Industry:Weather
(Abbreviated CLOS. ) A line of sight not obstructed by clouds or haze. Compare cloud-free line of sight.
Industry:Weather
A principal cloud type (cloud genus) composed of detached cirriform elements in the form of white, delicate filaments, of white (or mostly white) patches, or of narrow bands. These clouds have a fibrous aspect and/or a silky sheen. Many of the ice crystal particles of cirrus are sufficiently large to acquire an appreciable speed of fall; therefore, the cloud elements have a considerable vertical extent. Wind shear and variations in particle size usually cause these fibrous trails to be slanted or irregularly curved. For this reason, cirrus does not usually tend, as do other clouds, to appear horizontal when near the horizon. Because cirrus elements are too narrow, they do not produce a complete circular halo. Cirrus often evolves from virga of cirrocumulus or altocumulus (Ci cirrocumulogenitus or Ci altocumulogenitus), or from the upper part of cumulonimbus (Ci cumulonimbogenitus). Cirrus may also result from the transformation of cirrostratus of uneven optical thickness, the thinner parts of which dissipate (Ci cirrostratomutatus). It may be difficult at times to distinguish cirrus from cirrostratus (often impossible when near the horizon); cirrostratus has a much more continuous structure, and if subdivided, its bands are wider. Thick cirrus (usually cirrus spissatus) is differentiated from patches of altostratus by its lesser extension and white color. The term “cirrus” is frequently used for all types of cirriform clouds. See cloud classification, cirriform.
Industry:Weather
A system of physical units based on the use of the centimeter, the gram, and the second as elementary quantities of length, mass, and time, respectively. In this system, density is expressed in gm cm−3, speed in cm s−1, force in dynes (gm cm s−2, pressure in baryes (dynes cm−2), and energy in ergs (gm cm2s−2). While this is a popular system of units in nearly all fields of science and technology, some of the meter–kilogram–second system units are more convenient for certain meteorological applications.
Industry:Weather
A unit of luminous intensity expressed in lumen per steradian (lm sr−1). The candela was first defined as 1/60 the luminous intensity, in the perpendicular direction, of a 1 cm2 blackbody radiator at the freezing temperature of platinum (about 2042 K) and a pressure of 1 atmosphere. It is now defined as the luminous intensity of a light source producing single-frequency light at a frequency of 540 terahertz with a power of 1/683 watt per steradian. It is the standard unit of measure for luminous intensity adopted by the International System of Units (SI). In some texts, it is referred to as the international standard candle.
Industry:Weather
Line of sight that is unhampered by the clouds present. This is a military term and the data are used for determining the utility of various communications, surveillance, and weapons systems. Data express the probability that the line of sight will be unobstructed by clouds for geographic areas and climatic regions. Compare clear line of sight.
Industry:Weather
Any of several devices that measure the number concentration of atmospheric particles upon which water vapor condenses at low values of supersaturation that are equivalent to those that occur with the formation of tropospheric liquid clouds. The supersaturations produced in the condensation chambers of these devices can normally be set within a range from a few tenths of one percent to several percent. However, clouds or haze can begin to form on very hygroscopic particles at saturation levels well below 100%, so some devices also allow for a range of measurements at subsaturation. The concentrations of cloud condensation nuclei (CCN) are normally reported as the number per cubic centimeter of air activated at a specified super- or subsaturation with respect to water. Compare condensation nuclei counter.
Industry:Weather
The property that a finite-difference approximation is formulated in such a way that it has access to the information that is required to determine the solution of the corresponding differential equation; violating this condition leads to a numerical instability. As an example, suppose the solution to the differential equation is a wave traveling at speed c. If a finite-difference approximation is only able to access information on its grid that is traveling at speeds less than c, it violates the CFL condition and it will not be able to approximate the solution of the differential equation.
Industry:Weather
