- 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, ...
Depth corrections applied to sounding lines for any portion of the line above the water, when high velocities, great depth, insufficient sounding weight, etc. , result in large angles of inclination.
Industry:Weather
1. A widespread body of air, the properties of which can be identified as 1) having been established while that air was situated over a particular region of the earth's surface (airmass source region), and 2) undergoing specific modifications while in transit away from the source region. An air mass is often defined as a widespread body of air that is approximately homogeneous in its horizontal extent, particularly with reference to temperature and moisture distribution; in addition, the vertical temperature and moisture variations are approximately the same over its horizontal extent. The stagnation or long-continued motion of air over a source region permits the vertical temperature and moisture distribution of the air to reach relative equilibrium with the underlying surface. See airmass classification. 2. In radiation, the ratio of the actual path length taken by the direct solar beam to the analogous path when the sun is overhead from the top of the atmosphere to the surface. Extrapolation of surface measurements to zero air mass was the original method for estimating the value of solar irradiance at the top of the atmosphere. 3. See optical air mass.
Industry:Weather
A small, sensitive windmill anemometer having flat vanes. It indicates the number of linear feet (or meters) of air that have passed the instrument during its exposure.
Industry:Weather
An imaginary volume of air to which may be assigned any or all of the basic dynamic and thermodynamic properties of atmospheric air. A parcel is large enough to contain a very great number of molecules, but small enough so that the properties assigned to it are approximately uniform within it and so that its motions with respect to the surrounding atmosphere do not induce marked compensatory movements. It cannot be given precise numerical definition, but a cubic foot of air might fit well into most contexts where air parcels are discussed, particularly those related to static stability. Any fluid parcel may be defined similarly.
Industry:Weather
A local downdraft or an abrupt reduction of headwind or increase in tailwind that causes an airplane to drop suddenly.
Industry:Weather
The presence of substances in the atmosphere, particularly those that do not occur naturally. These substances are generally contaminants that substantially alter or degrade the quality of the atmosphere. The term is often used to identify undesirable substances produced by human activity, that is, anthropogenic air pollution. Air pollution usually designates the collection of substances that adversely affects human health, animals, and plants; deteriorates structures; interferes with commerce; or interferes with the enjoyment of life. Compare airborne particulates, designated pollutant, particulates, criteria pollutants.
Industry:Weather
The process of attempting to limit the amount of air pollution by regulating the emission of pollutants or their precursors. Control strategies are alternative long-term policies that could reduce air pollution, as projected using air-quality modeling. For primary pollutants such as sulfur dioxide, control strategies include burning cleaner low-sulfur coal, scrubbing sulfur dioxide from the combustion products before releasing them into the atmosphere, or changing to alternative fuels or processes. For secondary pollutants such as ozone that are not emitted directly but are created in the lower atmosphere by a complex series of chemical and photochemical reactions involving NOx and volatile hydrocarbons, control is achieved by changing the emissions of one or both of the primary reactants.
Industry:Weather
1. An extended period of a high concentration of pollutants in the atmosphere. 2. A public alert or notification of unhealthful air quality. In the U. S. , the degree of alert is often based on the pollutant standards index (PSI):
* Stage 1 episode or alert, for 200 ≤ PSI < 275. Public recommendation: avoid strenuous activities. Children and elderly people advised to stay indoors. * Stage 2 episode or alert, for 275 ≤ PSI < 400. Public recommendation: cease all physical activity, and stay indoors. Industry can be ordered to reduce emissions, and employees forced to carpool or use mass transportation for their necessary travel. * Stage 3 episode or alert, for PSI ≥ 400. Everyone ordered to remain at home with windows closed. Minimize physical exertion and avoid driving vehicles. Automobile travel could be restricted and industries ordered to reduce emissions.
Industry:Weather
The subdiscipline of meteorology devoted to the study of air pollution. Topics include sources of pollutants, emission rates, plume rise, fallout, dry and wet deposition, chemistry, precipitation scavenging, dispersion (molecular diffusion and turbulent transport), short- and long-range transport (advection), trapping, venting by cumulus clouds, complex terrain and mesoscale circulations, receptors, impact on society, alerts and episodes, policy and regulation, modeling, prediction, control, and climate change.
Industry:Weather
