Rayleigh (unit)

Rayleigh (unit)

The rayleigh is a unit of luminous flux used to measure air glow (auroras, for example). It was first proposed in 1956 by D. M. Hunten, noredlink|Franklin E. Roach, and J. W. Chamberlain. It is named for Robert John Strutt, 4th Baron Rayleigh (1875 – 1947).Fact|date=November 2007 Its symbol is R (also used for the röntgen, an unrelated unit). The SI prefixes are used with the rayleigh.

One rayleigh (1 R) is defined as a column emission rate of 1010 photons per square metre per column per second. Note that rayleigh is an apparent emission rate, as no allowances have been made for scattering or absorption. The night sky has a luminous intensity of about 250 R, while auroras can reach values of 1000 kR.

The relationship between radiance, "L", (in units of photons per square metre per second per steradian) and "I" (in units of rayleighs) is simply

:"L" = "I" × frac|1010|4π

References

* D. M. Hunten, Franklin E. Roach, and J. W. Chamberlain (1956), A photometric unit for the airglow and aurora, Journal of Atmospheric and Terrestrial Physics (GB), Volume 8, pp 345-346


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Rayleigh — may refer to:*Rayleigh (unit), named after the son of Lord Rayleigh *Rayleigh criterion in Angular resolution *Rayleigh distribution *Rayleigh fading *Rayleigh law on low field magnetization *Rayleigh length *Rayleigh number *Rayleigh quotient… …   Wikipedia

  • Rayleigh (unite) — Rayleigh (unité) Le rayleigh est une unité d intensité lumineuse de l ancien Système CGS, de symbole R[1] ; il correspond à la brillance d une source émettant dans toutes les directions un million de photons lumineux par seconde par… …   Wikipédia en Français

  • Rayleigh scattering — This article is about the optical phenomenon. For the magnetic phenomenon, see Rayleigh law. For the stochastic distribution, see Rayleigh distribution. For the wireless multipath propagation model, see Rayleigh fading. Rayleigh scattering causes …   Wikipedia

  • rayleigh — (R)    a CGS unit of light intensity used in astronomy and physics to measure the brightness of the night sky, auroras, etc. One rayleigh represents the light intensity of one million photons of light emitted in all directions per square… …   Dictionary of units of measurement

  • rayleigh — noun A unit of brightness (of the sky at night) equal to 10/4π quanta per square meter per second per steradian …   Wiktionary

  • John Strutt, 3rd Baron Rayleigh — Infobox Scientist name = Lord Rayleigh caption = John William Strutt, 3rd Baron Rayleigh birth date = Birth date|1842|11|12|df=yes birth place = Langford Grove, Maldon, Essex, England death date = Death date and age|1919|6|30|1842|11|12|df=yes… …   Wikipedia

  • Robert Strutt, 4th Baron Rayleigh — Robert John Strutt, 4th Baron Rayleigh (28 August 1875 ndash;13 December 1947) was a British peer and the son of the famous physicist John William StruttLike his father, Robert John Strutt was also a physicist. In fact, he has followed up his… …   Wikipedia

  • rayl — Unit of acoustic impedance. 1 r. = 1 kg × m−2 × sec−1. [Baron Rayleigh (John W. Strutt), Eng. physicist] …   Medical dictionary

  • light — light1 lightful, adj. lightfully, adv. /luyt/, n., adj., lighter, lightest, v., lighted or lit, lighting. n. 1. something that makes things visible or affords illumination: All colors depend on light. 2. Physics …   Universalium

  • analysis — /euh nal euh sis/, n., pl. analyses / seez /. 1. the separating of any material or abstract entity into its constituent elements (opposed to synthesis). 2. this process as a method of studying the nature of something or of determining its… …   Universalium

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”