- 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, ...
The angular difference between the horizontal and the direction to the horizon. Leaving aside displacements due to topography (mountains and valleys), the horizon can be displaced from the horizontal by the earth's curvature, by the elevation of the observer, and by the refraction of light in the atmosphere.
Industry:Weather
Dinitrogen pentoxide, N2O5, is formed from the reaction of the nitrate radical with nitrogen dioxide. It is, however, thermally unstable and is dissociated readily near the earth's surface to form its precursors. Higher in the atmosphere, it is an effective reservoir for active nitrogen. In solution it hydrolyzes to two nitric acid molecules. Removal of N2O5 on aqueous particles occurs very easily, causing an increase in acidity and a loss of active nitrogen (NO + NO2).
Industry:Weather
Property whereby the sign of the horizontal divergence reverses at least once in the troposphere or the stratosphere. This implies that the vertically integrated divergence and the associated surface pressure tendency are small residuals of much larger contributions.
Industry:Weather
An instrument for measuring radiant energy. The Dines radiometer consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a blackbody source with a temperature that can be varied. Equality of radiation is indicated by the balance of the differential thermometer. Compare bolometer; see actinometer, photometer, Tulipan radiometer.
Industry:Weather
A type of pressure-tube anemometer, named after the inventor, in which the pressure head is located on the windward end of the wind vane so that it is kept facing into the wind. The suction head is mounted concentrically with the shaft, near the bearing that supports the vane, and develops a suction that is independent of wind direction. The pressure difference between the suction head and the pressure head is proportional to the square root of the wind speed and is measured by a specially designed float manometer with a linear wind scale. The Dines anemometer was first described by William Henry Dines in 1892 and had all the essentials of the final form of the pressure-tube anemometer. With various modifications, the Dines anemometer remained a useful wind measuring device into the 1960s.
Industry:Weather
A rare and strong south foehn in the Alps, in which the strong foehn winds reach the ground only in the lower parts of the valleys and the plain or foreland. Under these conditions the sea level pressure difference between the south and north side of the Alps is greater than 12 mb. In the upper portions of the valleys, the surface winds are light and variable, as the strong winds do not penetrate to the ground. This effect has been attributed to the persistence of a cold-air layer in the upper valleys, decoupling the surface winds from the flow aloft and making the flow unable to follow the terrain in this region, or to the position of this region with respect to the long mountain wave that may accompany this foehn. The foehn wall and the precipitation area extend beyond the crest across the almost calm surface region in the upper valleys. This condition “is known as ‘dimmer-foehn,’ meaning blocked or dammed-up foehn. ”
Industry:Weather
A method of determining possible relationships between meteorological variables based on their dimensions. A systematic method called Buckingham Pi theory can be used to find such relationships. The results are often expressed as dimensionless groups, called Pi groups. While Buckingham Pi theory helps to identify the appropriate dimensionless groups, it cannot indicate the relationships between the groups. Such relationships must be found empirically, based on field or laboratory measurements of the dimensionless groups. When the empirical data are plotted on graphs of one dimensionless group versus another, often data from many disparate meteorological conditions will result in one common curve, yielding a similarity relationship that may be universal. Dimensional analysis has been used extensively and successfully in studies of the atmospheric boundary layer, where turbulence precludes other more precise descriptions of the flow because exact solutions of the equations of motion are impossible to find due to the closure problem.
Industry:Weather
Partially oxidized sulfur gas, formula (CH3)2SO, which finds large use as a solvent, but due to low volatility does not exist in the atmosphere in high concentrations. Found in marine aerosols, and thought to be a partial oxidation product of dimethyl sulfide.
Industry:Weather
Naturally occurring sulfur gas, formula CH3SCH3, emitted predominantly by phytoplankton, marine algae, seaweed, etc. Dimethyl sulfide (DMS) has the highest flux to the atmosphere of all biogenic sulfur gases. The oxidation of DMS has been linked to the formation of aerosol particles in the troposphere remote from urban areas, and thus to the potential for climate regulation.
Industry:Weather
Naturally occurring sulfur gas, formula CH3SSCH3; minor constituent in the natural sulfur cycle.
Industry:Weather
