- 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 term with several possible meanings but often that frequency of an incident electromagnetic wave at which the transmission characteristics of a medium change markedly. As ascribed to a layer in the ionosphere, it is the minimum frequency of a vertically directed radio wave that will penetrate the layer.
Industry:Weather
A term used to describe the range of Mach numbers between the buffeting Mach number and the stalling Mach number within which an aircraft must be operated. The buffeting and stalling Mach numbers approach each other with altitude; when they become the same, the ceiling of the aircraft is reached.
Industry:Weather
A term often used to describe satellite-viewed oceanic stratocumulus associated with an inversion. Closed-cell patterns are composed of cloud elements of almost hexagonal shape, bounded at their edges with a cloud-free space.
Industry:Weather
A temperature describing an emitter based on the best match of the shape of its emission spectrum to that of a blackbody at that temperature. The match may be over only a portion of the Planck curve (see Planck's law), or even by noting the wavelength of maximum emission and using Wien's displacement law. Unlike the brightness temperature, color temperature can be used to approximate the physical temperature of objects of unknown distance (especially stars) and also of isothermal emitters that are optically thin.
Industry:Weather
A technique for handling the complexity of spectral transmission in models of longwave radiative transfer. Rather than integrating the radiation wavelength by wavelength, absorption coefficients with similar values are first grouped together, and the results for each group are summed, taking into account the relative importance of the coefficients for different atmospheric layers. The technique is fairly accurate and greatly reduces the amount of computation time required.
Industry:Weather
A technique of pressure-pattern flight whereby an aircraft is navigated, in the direction of wind flow, along a height contour line on a constant-pressure surface, thereby assuring a continuous, nearly direct tailwind. This is accomplished by maintaining constant indicated altitude on the pressure altimeter along with constant absolute altitude above a level surface. The latter requirement restricts the use of this method to over-ocean flight.
Industry:Weather
A table for a specific location showing means, extremes, and other statistics including the number of occasions when specific meteorological conditions or specific values of a meteorological element were observed or when specific values of two or more meteorological elements were observed simultaneously during a specific number of years.
Industry:Weather
A table showing the joint or compound frequencies of occurrence of two or more variables or attributes. The simplest example is the so-called fourfold table in which two attributes A and B are each divided into two classes, say A1, A2, and B1, B2, thus giving rise to four possible combinations: (A1, B1), (A1, B2), (A2, B1), and (A2, B2). The contingency table then displays the frequency of each of the four combinations.
Industry:Weather
A sustained current in the lightning stroke that flows to the ground after the return stroke. Continuing currents can have durations in excess of 100 ms with magnitudes of typically 100 A. Continuing currents occur in negative and positive cloud-to-ground lightning flashes.
Industry:Weather
A sunshine recorder of the type in which the timescale is supplied by the motion of the sun. It consists essentially of a spherical lens that burns an image of the sun upon a specially prepared card. The instrument must be oriented carefully so that the timescale on the card agrees with the sun time. The depth and breadth of the trace may be interpreted in terms of the approximate intensity of the sun.
Industry:Weather
