- 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, ...
Literally “twilight rays,” these alternating dark and light bands (shadows and light scattered from sunbeams, respectively) seem to diverge fanlike from the sun's position during twilight. This apparent divergence of parallel sunlight is an artifact of linear perspective. Crepuscular rays may appear as 1) shadows cast across the purple light by high, distant cloud tops or 2) shadows next to light scattered from sunbeams by haze in the lower atmosphere. Sunbeams seen during the day are sometimes called crepuscular rays, even though they are observed outside twilight.
Industry:Weather
Literally “twilight rays,” these alternating dark and light bands (shadows and light scattered from sunbeams, respectively) seem to diverge fanlike from the sun's position during twilight. This apparent divergence of parallel sunlight is an artifact of linear perspective. Crepuscular rays may appear as 1) shadows cast across the purple light by high, distant cloud tops or 2) shadows next to light scattered from sunbeams by haze in the lower atmosphere. Sunbeams seen during the day are sometimes called crepuscular rays, even though they are observed outside twilight.
Industry:Weather
The scale of the migratory high and low pressure systems (or cyclone waves) of the troposphere with wave lengths of 1000–4000 km. Terminology in the literature is confusing, chiefly because cyclonic-scale disturbances at low levels are frequently associated with large-scale disturbances in the high troposphere. See barotropic instability, baroclinic instability.
Industry:Weather
(Abbreviation for ceiling and visibility unlimited (and unrestricted). ) An operational term no longer formally defined in meteorology, but still commonly used in aviation, that designates a condition wherein the ceiling is more than 10 000 ft and the visibility is more than 10 miles.
Industry:Weather
(Used in open channel flow. ) Natural or man-made physical properties at a location of a river or channel that determine the relationship between water surface elevation and discharge for some distance upstream and/or downstream of the site.
Industry:Weather
(Symbol Cl. ) A measure of the chloride content, by mass, of seawater (grams per kilogram of seawater, or per mille). Originally chlorinity was defined as the weight of chlorine in grams per kilogram of seawater after the bromides and iodides had been replaced by chlorides. To make the definition independent of atomic weights, chlorinity is now defined as 0. 3285233 times the weight of silver equivalent to all the halides. The chlorinity of seawater is generally determined in order to permit the calculation of salinity, although other methods of determining salinity can be used. By using normal water as a comparison standard, Knudsen burettes and pipettes for the analysis, and Knudsen's tables to compute the results, determinations as accurate as those of a time-consuming gravimetric analysis can be made with a rapid titration of the seawater against silver nitrate solution, employing potassium chromate or other suitable indicator for the end point. It is customary to express chemical analyses of seawater in terms of chlorinity or of chlorosity.
Industry:Weather
(Symbol C. ) The 12th element in the periodic table, mass 12. 000. Carbon is one of the most versatile elements and combines with itself and many other elements to form a huge variety of organic compounds, for example, hydrocarbons and their derivatives, some of which are found in the atmosphere. Elemental carbon occurs in the atmosphere, mostly in the form of soot from incomplete combustion of organic matter. Smoke particles also have a large proportion of carbonaceous material in them. Together, soot and smoke account for a large part of the reduction in visibility occurring over continental and polluted regions, due to light scattering and light absorption.
Industry:Weather
(Spanish term meaning “provider. ”) The name applied, in northern Spain, to the rain- bearing west wind.
Industry:Weather
In radar, the region in space that contains the targets that contribute to the received signal or echo arriving at a particular instant. The contributing region is a volume in space determined by the beamwidth and pulse length of the radar. Specifically, the contributing region is the volume defined by one-half the pulse length in the radial direction and the beamwidth in the transverse direction. See pulse volume.
Industry:Weather
A synoptic code used by combat aircraft to report observable meteorological elements in groups of five-digit numbers.
Industry:Weather
