| Section S | S index | 111-119 of 1376 terms |
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scattering matrixA 2 × 2 matrix comprising four signal amplitudes that characterizes the scattering from a target in terms of a polarization basis. The basis is defined by two orthogonal vectors, for example, horizontal and vertical or right and left circular. The diagonal terms are the amplitudes of the copolarized signals corresponding to the two transmitted polarizations, and the off-diagonal terms are the amplitudes of the cross- polarized signals. Each term carries a double subscript that denotes the transmitted and received polarization. Compare covariance matrix.
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scatteringIn a broad sense, the process by which matter is excited to radiate by an external source of electromagnetic radiation, as distinguished from emission of radiation by matter, which occurs even in the absence of such a source. By this definition, reflection, refraction, and even diffraction of electromagnetic waves are subsumed under scattering. Sometimes scattering is applied in a restricted sense to that radiation not accounted for by the laws of specular reflection and refraction, which are approximate because matter is not continuous on all scales. Often the term scattered radiation is applied to that radiation observed in directions other than that of the source and may also be applied to acoustic and other waves. If there is no change in frequency between the incident and scattered radiation, the scattering is sometimes said to be elastic; the converse is inelastic. Scattering is also applied to any interaction between particles that results in a change in direction. See multiple scattering, Mie theory, Rayleigh's scattering law.
Born, M., and E. Wolf, 1965: Principles of Optics, 3d rev. ed., 98–108.
Doyle, W. T., 1958: Am. J. Phys., 53, 463–468.
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scavenging by precipitationRemoval of pollutants from the air by either rain or snow. Rainout (or snowout), which is the in-cloud capture of particulates as condensation nuclei, is one form of scavenging. The other form is washout, the below-cloud capture of particulates and gaseous pollutants by falling raindrops. Large particles are most efficiently removed by washout. Small particles (especially those less than 1 μm in diameter) more easily follow the airstream flowing around raindrops and generally avoid capture by raindrops except in heavy rain events.
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scharnitzerA cold, northerly wind of long duration in Tirol.
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SchlernwindEast wind blowing down from the Schlern near Bozen in Tirol.
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schlierenParcels or strata of air having densities sufficiently different from that of their surroundings that they may be discerned by means of refraction anomalies in transmitted light. All of the natural scintillation phenomena in the atmosphere result from the presence of density schlieren developed by turbulent processes. The schlieren method is an experimental technique for optically detecting the presence of slight density, and hence temperature and/or pressure, variations in gases and liquids by virtue of refraction effects.
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