AM 1 sunlight

https://doi.org/10.1351/goldbook.A00313
Solar @I03254@ at sea level, i.e., traversing the atmosphere, when the direction of the sun is perpendicular to the surface of the earth. Also called terrestrial global irradiance.
See also:
AM 0 sunlight
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 302 [Terms] [Paper]