ACTINOMETRY
actinometry
(noun) measuring the intensity of electromagnetic radiation (especially of the sun’s rays)
Source: WordNet® 3.1
Etymology
Noun
actinometry (uncountable)
the measurement of the heating power of electromagnetic radiation, especially that of solar radiation
the measurement of the chemical or actinic energy of light
Source: Wiktionary
Ac`ti*nom"e*try, n.
1. The measurement of the force of solar radiation. Maury.
2. The measurement of the chemical or actinic energy of light. Abney.
Source: Webster’s Unabridged Dictionary 1913 Edition