An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 10 Search : radian
irradiance
  تابشداری   
tâbešdâri

Fr.: éclairement énergétique   

The → energy at all → wavelengths that is incident on unit area of surface in unit time. It is measured in Watts per square meter.

Irradiance, from ir- variant of → in- (by assimilation) before r + radi(ant), → radiation, + -ance a suffix used to form nouns either from adjectives in -ant or from verbs.

Tâbešdâri, from tâbeš, → radiation, + dâri, verbal noun from dâštan "to have, hold," → property.

radian
  رادیان   
râdiyân (#)

Fr.: radian   

A unit of angular measure; one radian is that angle with an intercepted arc on a circle equal in length to the radius of the circle.

From radi(us) + -an an originally adj. suffix.

radiance
  تابش‌مندی   
tâbešmandi

Fr.: luminance   

1) Generally, the → radiant energy per unit → solid angle per unit of → projected area of the → source. It is usually expressed in → watt per → steradian per → square  → meter (W m-2 sr-1). Same as steradiancy.
2) Of any particular → wavelength within the interval covered by a → spectral line, the → energy per unit → surface per steradian, per wavelength; denoted Iλ. The term radiance is often loosely replaced by "→ intensity." The radiance of the whole line is given by I = ∫ Iλ dλ. The radiance of an → emission line depends, among other things, upon the → number of → atoms per unit area in the → line of sight (the → column density) in the → upper level of the line.

From radia(nt), → radiant, + → -ance.

Tâbešmandi, noun from tâbešmand "possessing radiation," from tâbeš, → radiation, + -mand a suffix denoting possession; Mid.Pers. -ômand suffix forming adjectives of quality.

radiant
  ۱) تابنده، تابشی؛ ۲) تابسر   
1) tâbandé, tâbeši; 2) tâbsar

Fr.: radiant   

1) Sending out rays of light; bright; shining.
See also: → radiant energy, → radiant flux, → radiant intensity.
2) The point in the sky from which → meteors in a → meteor shower appear to radiate or come. See also: → radiant drift.

M.E., from M.Fr. radiant, from L. radiantem (nominative radians) "shining," pr.p. of radiare "to shine, radiate," → radiation.

1) Tâbandé, tâbeši adj. from tâbidan, → radiate.
2) Tâbsar, from tâb "light, radiation," → radiation, + sar "head, top, summit, point," → head.

radiant drift
  دلک ِ تابسر   
delek-e tâbsar

Fr.: dérive de radiant   

The apparent slow motion of the → radiant of a → meteor shower from night to night against the background stars due to the Earth moving in its orbit around the Sun.

radiant; → drift.

radiant energy
  کاروژ ِ تابشی   
kâruž-e tâbeši

Fr.: énergie radiative   

The energy that is transmitted in the form of → radiation, in particular as → electromagnetic radiation.

radiant; → energy.

radiant flux
  شار ِ تابشی   
šâr-e tâbeši (#)

Fr.: flux radiatif   

Rate of flow of energy as → radiation.

radiant; → flux.

radiant intensity
  درتنویی ِ تابشی   
dartanuyi-ye tâbeši

Fr.: intensité de rayonnement   

A measure of the amount of radiation emitted from a point expressed as the radiant flux per unit solid angle leaving this source.

radiant; → intensity.

solar irradiance
  تابشداری ِ خورشیدی   
tâbešdâri-ye xoršidi

Fr.: irradiation solaire   

The radiative power per unit area in all wavelengths from the Sun received by the Earth at its average distance from the Sun. Its mean value is called the → solar constant. The solar irradiance changes over a year by about 6.6% due to the variation in the Earth/Sun distance. Moreover, solar activity variations cause irradiance changes of up to 1%.

solar; → irradiance.

steradian (sr)
  استرادیان   
esterâdiân (#)

Fr.: stéradian   

The solid angle subtended at the center of a sphere by an area on its surface numerically equal to the square of the radius. → square degree.

From ste(reo)-, → stereo- + → radian.