- 行业: Weather
- Number of terms: 60695
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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 scale with the ice point at 0° and the boiling point of water at 80°, with pressure of one atmosphere.
Industry:Weather
A type of radar display on which the reflectivity or other properties of echoes are displayed as a function of range and elevation angle in polar coordinates. The RHI may be produced by scanning the antenna in elevation with the azimuth fixed, or it may be composed of data from successive PPI displays at different elevation angles. It may be an intensity modulated display or may use a scale of colors to represent the values of the function displayed.
Industry:Weather
The use of a radio direction finder to track precisely the angular position (azimuth and elevation) of a transmitter; often used as a method of determining upper-level winds represented by a radiosonde's movement during flight. See'' also'' wind finding.
Industry:Weather
Analog radar device used in the 1950s to provide the power spectrum of the fluctuations in the received signal intensity, which may be interpreted in terms of the relative velocities among the scatterers in the pulse volume. This approach was made obsolete when pulsed Doppler radar was introduced to meteorology in the late 1950s.
Industry:Weather
A prediction of the amount of precipitation that will fall at a given location in a given time interval.
Industry:Weather
The organization responsible for collection, analysis, interpretation, and publication of mean sea level data from a global network of gauges. PSMSL is one of the Federation of Astronomical and Geophysical Services, under the auspices of the International Council of Scientific Unions.
Industry:Weather
A relative scale developed by the U. S. Environmental Protection Agency that applies to specified air pollutants (ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulates), designed to clearly and simply inform the public of the current air quality. The scale is normalized such that an index value of 100 corresponds to the U. S. Federal air- quality standard for each specified pollutant. The minimum and maximum values are 0 and 500, corresponding to perfectly clean and extremely dirty air. Instead of presenting to the public different numbers for different pollutants, usually only the worst value is presented. The relationship between the pollutant standards index and health advisory level are: 0–50 Good; 50–100 Moderate; 100– 200 Unhealthful; 200–300 Very unhealthful; >300 Hazardous. See air pollution episode.
Industry:Weather
Clouds are cirrus or altocumulus lenticularis, and show very strong irisation similar to that of mother-of-pearl, especially when the sun is several degrees below the horizon. They occur at heights about 20–30 km above the earth. These clouds are rarely seen, and it would appear that they can be observed only in certain regions. They have been observed mainly over Antarctica due to the colder temperatures present there in the circumpolar vortex. They also form over Scotland and Scandinavia in winter during periods with an intense, broad, deep, and homogeneous westerly to northwesterly flow of air over northern Europe; they are also observed in Alaska. Less frequent sightings have been reported at lower latitudes. The simultaneous occurrence of various colors of the spectrum in more or less irregular patterns strongly suggests diffraction by spherical particles. The exact physical constitution of cloud particles has been determined by aircraft (e.g., the NASA ER2 aircraft) penetration showing the presence of nitric acid hydrates (in particular nitric acid tri-hydrate, type I) with the addition of water ice at temperatures a few degrees colder (type II). Nuclei for clouds are thought to be sulfuric acid aerosol, possibly of volcanic origin. The clouds form in regions where dynamic lifting or radiational cooling lowers the air to temperatures below saturation for these different constituents (about −95°C). PSC are thought to play a major role in the formation of the “ozone hole” because they absorb odd nitrogen from the atmosphere, which allows the catalytic destruction of ozone to occur. Nacreous clouds appear stationary and, by day, often resemble pale cirrus. At sunset, all the colors of the spectrum appear; as the sky darkens after sunset, they increase in brilliance. As the sun drops lower and lower below the horizon and the clouds are lighted by last rays, the various colors are replaced by a general coloration that is first orange and then becomes pink, contrasting vividly with the darkening sky. The clouds next become gray and the colors of the spectrum reappear but very weakly, then fade out rapidly. Later, up until about two hours after sunset, the nacreous clouds can still be distinguished standing out against the starry sky as tenuous and gray clouds. They can even be observed all night if there is moonlight. Before dawn, the same series of aspects appear, but in reverse order.
Industry:Weather
The rate at which pulses of radio energy are transmitted by a pulsed radar. The PRF determines the maximum unambiguous range and the maximum unambiguous Doppler velocity measurable by a particular radar. For typical weather radars, the PRF is in the range from several hundred hertz to several kilohertz.
Industry:Weather
A type of radar display on which the reflectivity or other properties of echoes are plotted in plan position, forming a maplike display, with radial distance from the center representing range and the angle of the radius vector representing azimuth angle. The PPI is usually produced by scanning the antenna in azimuth with the elevation fixed. It may be an intensity-modulated display or may use a scale of colors to represent the values of the function displayed.
Industry:Weather
