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Rayleigh (unit), a unit of photon flux named after the 4th Baron Rayleigh; Rayl, rayl or Rayleigh, two units of specific acoustic impedance and characteristic acoustic impedance, named after the 3rd Baron Rayleigh; Rayleigh criterion in angular resolution; Rayleigh distribution; Rayleigh fading; Rayleigh law on low-field magnetization; Rayleigh ...
The rayleigh is a unit of photon flux, used to measure faint light emitted in the sky, such as airglow and auroras. It was first proposed in 1956 by Donald M. Hunten, Franklin E. Roach, and Joseph W. Chamberlain. [1] It is named for Robert Strutt, 4th Baron Rayleigh (1875–1947). [2] Its symbol is R (also used for the röntgen, an unrelated unit).
In optics, Rayleigh proposed a well-known criterion for angular resolution. His derivation of the Rayleigh–Jeans law for classical black-body radiation later played an important role in the birth of quantum mechanics (see ultraviolet catastrophe). Rayleigh's textbook The Theory of Sound (1877) is still used today by acousticians and
In probability theory and statistics, the Rayleigh distribution is a continuous probability distribution for nonnegative-valued random variables. Up to rescaling, it coincides with the chi distribution with two degrees of freedom .
Rayleigh scattering causes the blue color of the daytime sky and the reddening of the Sun at sunset. Rayleigh scattering (/ ˈ r eɪ l i / RAY-lee) is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation.
Rayleigh waves are a type of surface acoustic wave that travel along the surface of solids. They can be produced in materials in many ways, such as by a localized impact or by piezo-electric transduction , and are frequently used in non-destructive testing for detecting defects.
Robert John Strutt, 4th Baron Rayleigh FRS [1] (28 August 1875 – 13 December 1947) was a British peer and physicist. He discovered "active nitrogen" and was the first to distinguish the glow of the night sky.
In fluid mechanics, the Rayleigh number (Ra, after Lord Rayleigh [1]) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free (or natural) convection. [ 2 ] [ 3 ] [ 4 ] It characterises the fluid's flow regime: [ 5 ] a value in a certain lower range denotes laminar flow ; a value in a higher range ...