NOTE: This definition was changed in RP-16-17 Addendum 2. Deletions have a strike-through. New text is old.
Irradiance produced by extraterrestrial solar radiation on a surface perpendicular to the sun’s rays at the mean Sun-Earth distance.
*International Lighting Vocabulary, CIE S 017/E:2011. Vienna: International Commission on Illumination; 2011.« Back to Definitions Index