Thanks to authorization from the International Commission of Illumination (CIE),
some of the definitions have been reproduced from the CIE International
Lighting Vocabulary, publication 17.4-1987.
Access the CIE web site.




hauteur angulaire (FR)
Höhenwinkel (DE)
altura angular (ES)
altezza angolare (IT)
elevasjonsvinkel (NO)


elevation angle

Unit: degree

Altitude angle above horizon of a point in the sky hemisphere. Also called altitude angle.

équation du temps (FR)
Zeitgleichung (DE)
équación del tiempo (ES)
equazione del tempo (IT)
tidsjevning (NO)


equation of time

Unit: minute

The equation of time describes the difference between clock time and true solar time due to the eccentricity in the earth's orbit and the tilt of the earth's axis with respect to the ecliptic plane. It is computed according to the recommendations of the Illuminating Engineering Society of North America, IES Journal N°13(4), 1984:

Where is the day of the year also called the Julian day (from 1 to 365, or 366 if the year is bissextile).

éclairement énergétique
normal extraterrestre (FR)
extraterrestrische direkt
normale Einstrahlung (DE)
irradiancia normal extraterrestre (ES)
illuminamento energetico
normale extraterrestre (IT)
ekstraterrestrisk vinkelrett
irradians (NO)

extraterrestrial normal irradiance

Unit: W/m2

Irradiance produced by the sun, on a surface perpendicular to its rays, on the outer limit of the Earth's atmosphere. The product of the solar constant by the sun-earth distance correction factor.

rayonnement solaire
extraterrestre (FR)
extraterrestrische
Solarstrahlung (DE)
radiación solar extraterrestre (ES)
radiazione solare extraterrestre (IT)
buitenaardse zonnestraling (NL)
ekstraterrestrisk solstråling (NO)
extraterrester solstralning (SE)


 

extraterrestrial solar radiation

CIE. Solar radiation incident on the outer limit of the Earth's atmosphere.

système d'information
géographique (FR)
Geografisches
Informationssystem (DE)

 

geographic information system

A Geographic Information System (GIS) is an organized collection of software and geographic data designed to manipulate, analyze, and display all forms of geographically referenced information.

satellite géostationnaire (FR)
Geostationärer Satellit (DE)

 

geostationary satellite

An artificial satellite that travels above the equator and at the same speed as the earth rotates, so that the satellite constantly overlooks the same part of the earth.

éclairement énergétique
global horizontal (FR)
globale horizontale Einstrahlung (DE)
irradiancia horizontal global (ES)
illuminamento energetico
orizontale globale (IT)
global horisontal stråling (NO)


global horizontal irradiance

Unit: W/m2

Irradiance produced by solar radiation on a horizontal surface on the earth.

rayonnement solaire global (FR)
Globalstrahlung (DE)
radiación solar global (ES)
radiazione solare globale (IT)
totale zonnestraling (NL)
globalstråling (NO)
promieniowanie sloneczne
calkowite (PL)
globalstralning (SE)


 

global solar radiation

CIE. Sum of direct solar radiation and diffuse solar (sky) radiation.

Greenwich (FR)
Greenwich (DE)
Greenwich (ES)
Greenwich (IT)
Greenwich (NL)
Greenwich (NO)
Greenwich (PL)
Greenwich (SE)


 

Greenwich

Borough of East Greater London in England, located at a latitude of 51.47°N and a longitude of exactly 0°.

albédo du sol (FR)
Bodenreflektivität (DE)
albedo del suelo (ES)
albèdine del suolo (IT)
bakkealbedo (NO)


ground albedo

Unit: 1

Ratio of the radiant flux reflected by the ground to the incident flux.

éclairement lumineux (FR)
Beleuchtungsstärke (DE)
iluminancia (ES)
illuminamento (IT)
verlichtingssterkte (NL)
belysningsstyrke; illuminans (NO)
natezenie oswietlenia (PL)
illuminans; belysningsstyrka (SE)


illuminance (at a point of a surface)

Unit : lx

CIE. Quotient of the luminous flux incident on an element of the surface containing the point, by the area of that element.

Equivalent definition. Integral, taken over the hemisphere visible from the given point, of the expression where is the luminance at the given point in the various directions of the incident elementary beams of solid angle and is the angle between any of these beams and the normal to the surface at the given point.



éclairement énergétique (FR)
Bestrahlungsstärke;
Einstrahlung (DE)
irradiancia (ES)
illuminamento energetico (IT)
bestralingssterkte (NL)
irradians (NO)
natezenie napromienienia (PL)
irradians (SE)


irradiance (at a point of a surface)

Unit: W/m2

CIE. Quotient of the radiant flux incident on an element of the surface containing the point, by the area of that element.

Equivalent definition. Integral, taken over the hemisphere visible from the given point, of the expression where is the radiance at the given point in the various directions of the incident elementary beams of solid angle and is the angle between any of these beams and the normal to the surface at the given point.



courbe isoéclairement lumineux (FR)
Isolux-Linie (DE)
curva iso-iluminancia (ES)
curva isoilluminamento (IT)
isolux lijn (NL)
isoluxkurve (NO)
izoluksa; krzjwa izoluksów (PL)
isoluxkurva (SE)


iso-illuminance curve; isolux curve or line

CIE. Locus of points on a surface where the illuminance has the same value.

isotrope (FR)
isotrop (DE)
isotrop (NO)

isotropic

Having NO dependence on direction or angle.

latitude (FR)
geografische Breite (DE)
latitud (ES)
latitudine (IT)
breddegrad (NO)


latitude

Unit: degree

The angular distance north or south from the earth's equator measured through 90 degrees. The latitude is taken positive in the northern hemisphere.

longitude (FR)
geografische Länge (DE)
longitud (ES)
longitudine (IT)
lengdegrad (NO)


longitude

Unit: degree

The arc or portion of the earth's equator intersected between the meridian of a given place and a reference meridian (usually the one from Greenwich, England). The longitude is taken positive east of the Greenwich meridian and negative west of the Greenwich meridian.

lumen (FR)
Lumen (DE)
lumen (ES)
lumen (IT)
lumen (NL)
lumen (NO)
lumen (PL)
lumen (SE)


lumen

CIE. SI unit of luminous flux. Luminous flux emitted in unit solid angle (steradian) by a uniform point source having a luminous intensity of 1 candela. (9th General Conference of Weights and Measures, 1948).

Equivalent definition. Luminous flux of a beam of monochromatic radiation whose frequency is 540 1012 hertz and whose radiant flux is 1/683 watt.

luminance lumineuse (FR)
Leuchtdichte (DE)
luminancia (ES)
luminanza (IT)
luminantie (NL)
luminans (NO)
luminancja swietlna (PL)
luminans (SE)


luminance (in a given direction, at a given point of a real or imaginary surface)

Unit: cd/m2

CIE. Quantity defined by the formula:

Where is the luminous flux transmitted by an elementary beam passing through the given point and propagating in the solid angle containing the given direction : is the area of a section of that beam containing the given point: is the angle between the normal to that section and the direction of the beam.

efficacité lumineuse
d’un rayonnement (FR)
photometrisches
Strahlungsäquivalent;
Lichtausbente (DE)
eficacia luminosa
de una radiacion (ES)
coefficiente di visibilità
di una radiazione (IT)
fotometrisch
stralingsequivalent (NL)
lysekvivalent for stråling (NO)
skutecznosc swietlna
promieniowania (PL)
ljusekvivalent för stralning (SE)


luminous efficacy of radiation

Unit: lm/W

CIE. Quotient of the luminous flux , by the corresponding radiant flux :

When applied to monochromatic radiations, the maximum value of for photopic vision is:



flux lumineux (FR)
Lichtstrom (DE)
flujo luminoso (ES)
flusso luminoso (IT)
lichtstroom (NL)
lysfluks (NO)
strumien swietlny (PL)
ljusflöde (SE)


luminous flux

Unit: lm

CIE. Quantity derived from radiant flux by evaluating the radiation according to its action upon the CIE standard photometric observer. For photopic vision:

where is the spectral distribution of the radiant flux and is the spectral luminous efficiency.

lux (FR)
Lux (DE)
lux (ES)
lux (IT)
lux (NL)
lux (NO)
luks (PL)
lux (SE)


lux

Unit: lm/m2

CIE. SI unit of illuminance: llluminance produced on a surface of area 1 square meter by a luminous flux of 1 lumen uniformly distributed over that surface. A non-metric unit is the lumen per square foot lm/ft2 also called the footcandle (fc) equal to 10.764 lx.