| 释义 |
Rayleigh Physics.|ˈreɪlɪ|
[The title of J. W. Strutt, 3rd Lord Rayleigh (1842–1919), English physicist.]
1. Used, usu. attrib., to designate various concepts, devices, and phenomena he invented or investigated, as 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 other; Rayleigh disc, 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; Rayleigh instability (see quot. 1977); also called Rayleigh–Taylor instability [Sir Geoffrey Taylor (1886–1975), English mathematician]; Rayleigh limit, 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 (which corresponds to no path difference); Rayleigh number, a dimensionless parameter that is a measure of the instability of a layer of fluid due to differences of temperature and density at the top and bottom (see quot. 1950); Rayleigh scattering, 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); so Rayleigh-scattered a.; Rayleigh wave, a type of wave that travels over the surface of a solid with a speed independent of its wavelength, the motion of the particles being in ellipses so that the surface undulates.
1937Jenkins & White Fund. Physical Optics v. 123 Extending Rayleigh's criterion for the resolution of diffraction patterns..to the circular aperture, two patterns are said to be resolved when the central maximum of one falls on the first dark ring of the other. Ibid. vii. 159 The Rayleigh criterion for resolving of images. 1970D. W. Tenquist et al. University Optics II. v. 197 The chromatic resolving power of a prism, defined as λ/δλ where δλ is the smallest change of wavelength discernable [sic] in accordance with the Rayleigh criterion at a mean wavelength λ, is given by [etc.].
1913Physical Rev. I. 309 (heading) A method of producing known relative sound intensities and a test of the Rayleigh disk. 1972J. M. Taylor tr. Meyer & Neumann's Physical & Appl. Acoustics vi. 209 The Rayleigh disk..is practically never used any more to determine particle velocity, which can be derived much more quickly and conveniently from electroacoustic sound pressure measuring devices.
1961S. Chandrasekher Hydrodynamic & Hydromagnetic Stability x. 428 An important special case..is that of two fluids of different densities superposed one over the other (or accelerated towards each other); the instability of the plane interface between the two fluids, when it occurs (particularly in the second context), is called Rayleigh–Taylor instability. 1971I. G. Gass et al. Understanding Earth xix. 277/1 A Rayleigh instability..does not necessarily depend upon the existence of a density inversion... Where the depth of the fluid is very large, the fluid at the bottom is compressed by the overlying fluid and, in many cases, an instability develops before the temperature is high enough to produce a density inversion. 1977Sci. Amer. Oct. 144/2 The instability at the interface between a denser fluid overlying a lighter fluid, when the interface is otherwise in hydrostatic equilibrium, is called a Rayleigh instability (or sometimes a Rayleigh-Taylor instability).
1923Glazebrook Dict. Appl. Physics IV. 216/1 The adoption of the Rayleigh limit thus makes it possible considerably to increase the aperture of a lens system of any given type and to come close to the full theoretical resolving power with systems which, judged geometrically, would appear hopelessly over- or under-corrected. 1976Sci. Amer. Aug. 77/2 Ideally a lens should be at the Rayleigh limit for light of all wavelengths.
1950O. G. Sutton in Proc. R. Soc. A. CCIV. 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. 1980Sci. Amer. July 82/2 Convection begins when the Rayleigh number exceeds a critical value.
1971Physics Bull. July 387/1 More detailed studies of the linewidths of Rayleigh scattered lines can provide hitherto inaccessible information on the behaviour of fluids near their critical point or in the neighbourhood of phase transitions.
1937Jenkins & White Fund. Physical Optics xii. 280 The first quantitative study of the laws of scattering by small particles was made in 1871 by Lord Rayleigh, and such scattering is frequently called Rayleigh scattering. 1973C. Sagan Cosmic Connection (1975) xiii. 90 The beauty of the sunset, the sky, and distant landscapes are all due to Rayleigh scattering.
1920A. E. H. Love Treat. Math. Theory Elasticity (ed. 3) xiii. 313 The waves travel over the surface with a velocity, which is independent of the wave-length 2π/f, and slightly less than the velocity of equivoluminal waves propagated through the body. Waves of this kind are often called ‘Rayleigh-waves’. 1956J. C. Jaeger Elasticity, Fracture & Flow iii. 135 Rayleigh waves are not the only simple type of surface wave which can be predicted and identified. 1971I. G. Gass et al. Understanding Earth xxiv. 336/1 (caption) A Rayleigh wave from an earthquake in Columbia recorded in Montana.
2. Astr. Also rayleigh. A unit of luminous intensity equal to one million photons per square centimetre per second.
1956D. M. Hunter et al. in Jrnl. Atmospheric & Terrestrial Physics VIII. 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). 1970Nature 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. 1974Science 25 Jan. 317 A two-channel ultraviolet photometer aboard Pioneer 10 has made several observations of the ultraviolet glow in the wave⁓length range from 170 to 1400 angstroms in the vicinity of Jupiter. Preliminary results indicate a Jovian (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. |