Solar irradiance in space just above the atmosphere of the earth on a plane perpendicular to the direction of the sun (air mass,
AM, zero). Also called extraterrestrial irradiance.
See also: AM 1 sunlight
Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 302 (https://doi.org/10.1351/pac200779030293)