- 行业: Weather
- Number of terms: 60695
- Number of blossaries: 0
- Company Profile:
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 network of lightning detection equipment for locating the electromagnetic sources of a lightning flash. The flash, both intracloud and cloud-to-ground, is mapped in three-dimensional space using equipment with a time resolution of less than 1 μs. Since cloud-to-cloud and cloud-to-air are rare lightning phenomena, mapping them has little or no importance.
Industry:Weather
A narrow, not necessarily navigable, crack in pack ice that may widen into a lead.
Industry:Weather
A model designed to follow one parcel of air along its trajectory through the atmosphere. In the model, the air parcel undergoes chemical change, as well as being impacted by dilution and the injection of fresh pollutants.
Industry:Weather
A mirage in which the image of distant objects is displaced upward. Because the displacement increases with distance, a horizontal surface, such as that of a body of water, appears to bend upward and one's perception is that of being inside a broad shallow bowl. Indeed, the upward bending surface results in an (optical) horizon that can be much farther from the observer than in the absence of a mirage. Looming is an example of a superior mirage. The opposite of looming is sinking. Looming occurs when the concave side of light rays from a distant object is down, and this in turn occurs when the refractive index of the atmosphere decreases with height. This is very common, but the displacement is usually sufficiently small as to be unremarkable. However, when there is a temperature inversion over the surface, the looming can be striking.
Industry:Weather
A mirage in which the image (or images) is displaced laterally from the position of the object. This is not a difficult mirage to find, especially along the sun-warmed walls of buildings. In many cases, it appears as nothing but an inferior mirage turned on its side. However, there are often interesting subtleties. Easiest to find, perhaps, are the high-order multiple images that result from inhomogeneities along the wall. These can arise both from the wall having a slightly wavy surface and from the periodic variations in the internal structure of the wall that alter the thermal conductivity and so produce periodic temperature variations. Curiously, unlike the inferior mirage, the lateral mirage seems to be capable of producing three images even in the absence of inhomogeneities. The temperature profiles normal to horizontal and vertical surfaces are slightly different. In the case of the inferior mirage, gravity acts normal to the surface, while in the case of the lateral mirage, gravity is parallel to the surface. This produces a flow up the wall that results in a temperature profile capable of giving the three-image mirage. Lateral temperature gradients in the free atmosphere, away from vertical surfaces, are not sufficient to produce lateral mirages; the rare reports of such sightings undoubtedly arose from misinterpretations of observations.
Industry:Weather
A mesoscale zone of anticyclonically turning winds that develops downstream of the Cheyenne Ridge in northeast Colorado and southeast Wyoming, and is often centered just east of the foothills of the Rocky Mountains near the town of Longmont, Colorado. The cause of the feature is the interaction of the ambient low level northwest flow with the east–west terrain feature known as the Cheyenne Ridge. See also Denver convergence–vorticity zone.
Industry:Weather
A measure of the total effect of an absorption or emission line. The line intensity is equal to the integration of the absorption coefficient over the entire shape of the absorption line.
Industry:Weather
A measure of the finite width of a spectral line taken as the distance between the two points either side of the line center where the absorption has dropped to half of its value at the center. Transmission of atmospheric radiation is affected by line width, especially in the lower troposphere where line widths become large due to pressure broadening.
Industry:Weather
