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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | |
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First Edition Preface Second Edition Preface Acknowledgments
Section E E index 481-489 of 498 terms
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extinction cross section—(Also called attenuation cross section, especially for radar and radio wave propagation.) The area that, when multiplied by the irradiance of electromagnetic waves incident on an object, gives the total radiant flux scattered and absorbed by the object. Customary usage in radar describes the attenuation cross section as the area that, when multiplied by the power density of incident plane-wave radiation, gives the power removed from the beam by absorption and scattering. For a propagation medium consisting of a dispersion of scattering and absorbing objects, the volume extinction coefficient (m2m−3 or m−1) at a given location in the medium is the sum of the extinction cross sections of all the objects in a unit volume centered at the location. Compare scattering cross section, absorption cross section.
extinction—(Sometimes called attenuation.) The removal of radiant energy from an incident beam by the processes of absorption and/or scattering.
extraordinary ray—(Or extraordinary wave.) See ordinary ray.
extrapolation—The extension of a relationship between two or more variables beyond the range covered by knowledge, or the calculation of a value outside that range. In synoptic meteorology, extrapolation commonly refers to the forecasting of the position of a weather-pattern feature based solely upon recent past motion of that feature. Compare interpolation.
extraterrestrial radiation—Electromagnetic energy in a specified frequency band originating from sources other than those related to the earth, for example, cosmic or solar radiation.
extratropical cyclone—(Sometimes called extratropical low, extratropical storm.) Any cyclonic-scale storm that is not a tropical cyclone, usually referring only to the migratory frontal cyclones of middle and high latitudes. Compare subtropical cyclone.
extratropical low—Same as extratropical cyclone.
extratropical storm—Same as extratropical cyclone.
extratropical—In meteorology, typical of occurrences poleward of the belt of tropical easterlies.
extreme temperature—Same as temperature extremes. See also absolute temperature extremes.
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