单词 | rayleigh |
释义 | Rayleighn.1 Physics. attributive and in the genitive. Designating concepts, devices, and phenomena discovered, invented, or investigated by Lord Rayleigh. 1. Rayleigh wave n. a type of wave that propagates on the surface of a solid with a speed independent of its wavelength, the motion of the particles being in ellipses such that the surface undulates.Described by Rayleigh in 1887 ( Proc. London Math. Soc. 17 4). The ellipses of motion are in planes normal to the surface and parallel to the direction of propagation. ΘΚΠ the world > matter > physics > mechanics > types of motion > [noun] > wave > types of wave long wave1792 internal wave1804 stationary wave1833 solitary wave1838 standing wave1845 travelling wave1845 pressure wave1871 ripple1871 surface wave1887 sine wave1893 Rayleigh wave1903 shock wave1907 spherical wave1907 Love wave1924 bow shock1938 Rossby wave1951 soliton1965 1903 H. Lamb in Proc. Royal Soc. 72 129 Its velocity is that of free Rayleigh waves, and is accordingly somewhat less than that of waves or transversal displacement. 1920 A. E. H. Love Treat. Math. Theory Elasticity (ed. 3) xiii. 313 The waves travel over the surface with a velocity, which is..slightly less than the velocity of equivoluminal waves propagated through the body. Waves of this kind are often called ‘Rayleigh-waves’. 1956 J. C. Jaeger Elasticity, Fracture & Flow iii. 135 Rayleigh waves are not the only simple type of surface wave which can be predicted and identified. 1971 I. G. Gass et al. Understanding Earth xxiv. 336/1 (caption) A Rayleigh wave from an earthquake in Columbia recorded in Montana. 1996 Nature 23 May 275/1 In Plexiglas, for example, the Rayleigh wave speed is around 1,000 metres per second, but cracks never exceed 600 metres per second. 2. Rayleigh disc n. a lightweight disc suspended by a fine thread so that when it is placed at an angle to incident sound waves their intensity can be calculated from the measured torque on the disc. ΘΚΠ the world > matter > physics > science of sound > [noun] > instrument measuring intensity radiometer1905 Rayleigh disc1913 sound meter1928 1913 Physical Rev. 1 309 (heading) A method of producing known relative sound intensities and a test of the Rayleigh disk. 1932 P. E. Sabine Acoustics & Archit. vi. 111 The relative outputs of the source for different values of the input current were measured by placing the sound source together with a Rayleigh disk inside a box lined with highly absorbent material. 2000 Physica B 280 9/2 It would be nice to establish counterflow by direct observation using a Rayleigh disc, which had been previously done in He II. 3. Rayleigh criterion n. (also Rayleigh's criterion) the criterion by which adjacent lines or rings of equal intensity in a diffraction pattern are regarded as resolved when the central maximum of one coincides with the first minimum of the next. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > diffraction > [noun] > law or condition Bragg1913 Rayleigh criterion1917 Laue condition1966 1917 Trans. Optical Soc. 18 191 The original form [of the objective] gave definition just outside the limits of Rayleigh's criterion. 1937 F. A. Jenkins & H. E. White Fund. Optics vii. 159 The Rayleigh criterion for resolving of images. 1985 Internat. Jrnl. Heat & Fluid Flow 6 4/2 Rayleigh's criterion dictates that a cut-off slit 0.5 mm wide causes such serious diffraction spreading that [etc.]. 2004 D. Pugh Changing Sea Levels iii. 63 The Rayleigh criterion is a good guide for tidal analyses of continental shelf data from middle and high latitudes. 4. Rayleigh limit n. (a) the upper limit of a quarter of a wavelength placed on the difference between the optical paths of the longest and shortest rays of those going to form an image in order that the definition shall be close to the ideal; (b) the limit on resolving power arising from the Rayleigh criterion. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > emission of light, radiation > [noun] > optical path optical path1893 optical length1894 path length1900 Rayleigh limit1922 eikonal1923 1922 Trans. Optical Soc. 23 88 At the ‘Rayleigh limit’ when the residuals at the best focus amount to ¼λ..20 per cent. of the light has disappeared from the central disc. 1943 Proc. Royal Soc. A. 184 48 For a [crystal] face 1 mm. wide the smallest angle that can be measured by simple reflexion (Rayleigh limit) is 2 min. of arc. 1947 A. J. Thompson Making your own Telescope vi. 77 Experience has shown..that images quite reasonably approaching the same degree of perfection will be obtained if the difference in light path does not exceed twice the Rayleigh limit, or one half of a wave length. 1976 Sci. Amer. Aug. 77/2 Ideally a lens should be at the Rayleigh limit for light of all wavelengths. 2000 Science 6 Oct. 29/3 As microcircuitry grows ever finer, chipmakers run smack into the Rayleigh limit, which dictates that the smallest feature a light beam can write on a chip is half the wavelength of the light. 5. a. Rayleigh scattering n. the scattering of light by particles small compared with its wavelength, the intensity of the scattered light being inversely proportional to the fourth power of the wavelength (and therefore much greater for blue light than for red). ΘΚΠ the world > matter > physics > electromagnetic radiation > light > refraction > [noun] > scattering scattering1866 Rayleigh scattering1925 Thomson scattering1935 scatter1942 1925 Science 6 Mar. 264/2 It seems very doubtful that the combination frequencies can be detected in the case of ordinary Rayleigh scattering. 1973 C. Sagan Cosmic Connection (1975) xiii. 90 The beauty of the sunset, the sky, and distant landscapes are all due to Rayleigh scattering. 1993 K. S. Robinson Green Mars (new ed.) 183 Outside the glary cone of his headlamp's beam, the ice was an intense cobalt blue, an effect caused by the same Rayleigh scattering that blued the colour of the sky. b. Rayleigh-scattered adj. scattered as a result of Rayleigh scattering. ΚΠ 1950 Proc. Physical Soc. A. 63 1200 There is..some uncertainty in estimating the absorption of the Rayleigh scattered gamma-rays in the scatterer itself. 2005 Jrnl. Physics D 38 1923 A triple grating spectrograph was used to suppress the false stray light and Rayleigh scattered photons. 6. Rayleigh number n. a dimensionless parameter that is a measure of the instability of a layer of fluid arising from differences of temperature and density at the top and bottom, and is indicative of whether convection can occur in the fluid.A higher value of the parameter corresponds to an increased likelihood of convection. ΘΚΠ the world > matter > physics > mechanics > fluid mechanics > [noun] > specific numbers or quantities Reynolds number1910 Weber number1937 magnetic Reynolds number1950 Rayleigh number1950 1950 O. G. Sutton in Proc. Royal Soc. A. 204 298 The existence of a sustained convective regime depends upon the value of the non-dimensional quantity Ra = −βgαh4/κν, which we shall call the Rayleigh number. 1990 P. Kearey & F. J. Vine Global Tectonics x. 219 For convection in the mantle, which is a spherical shell overlain by a rigid lithosphere, the Rayleigh number corresponding to the onset of convection increases to 2380. 1999 Guardian 2 Sept. (Online section) 12/6 There is a number which characterises convective flow—the Rayleigh number—which is very large for systems such as the atmosphere and the oceans, and cannot be mimicked in the laboratory. 7. Rayleigh instability n. (a) = Rayleigh–Taylor instability at Rayleigh–Taylor n.; (b) the instability of a jet of liquid that tends to break up into droplets as a result of the surface tension of the liquid. ΚΠ 1957 Proc. Royal Soc. A. 241 22 On account of the mutual friction, the onset of the natural Rayleigh instability of the superfluid is also delayed. 1989 Nature 27 July 266/2 A long, thin thread of liquid is unstable (the Rayleigh instability) and should break up into a series of drops. 1998 Physics of Fluids 10 1846/1 In certain disease states..airway obstruction by fluid blockage may occur, perhaps due to a Rayleigh instability of the lining fluid. 2002 J. Colls Air Pollution (ed. 2) iv. 207 The Rayleigh instability which breaks up the jet into droplets occurs at the imposed frequency, and the droplet diameter can be calculated directly. This entry has been updated (OED Third Edition, December 2008; most recently modified version published online March 2022). rayleighn.2 Astronomy. A unit of luminous intensity or brightness used esp. for aurorae and planetary objects, equal to one million photons per square centimetre of a vertical column per second. ΘΚΠ the world > matter > physics > electromagnetic radiation > light > intensity of light, luminosity > [noun] > unit of light intensity lux1889 lumen1898 L1915 Lambert1915 phot1917 new candle1938 candela1950 cd1950 rayleigh1956 1956 D. M. Hunten et al. in Jrnl. Atmospheric & Terrestr. Physics 8 345 We suggest that 4πB be given the unit of ‘rayleigh’ (symbol R), where B is in units of 106 quanta/cm2 sec sterad. Hence 1R = 106 quanta/cm2 (column) sec. (The word ‘column’ is often inserted into these units to convey the concept of an emission-rate from a column of unspecified length). 1970 Nature 2 May 435/2 In the direction of maximum intensity the Lyman-α flux is 160 Rayleighs, which can be regarded as typical for the direction of the solar apex. 1974 Science 25 Jan. 317 Preliminary results indicate a Jovian hydrogen (1216 angstrom) glow with a brightness of about 1000 rayleighs and a helium (584 angstrom) glow with a brightness of about 10 to 20 rayleighs. 2005 Icarus 178 350 (caption) Emission intensity is indicated by a false color scale, and contour levels are 5, 10, 20, and 50 Rayleighs. This entry has been updated (OED Third Edition, December 2008; most recently modified version published online March 2022). < n.11903n.21956 |
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