actinometry

from WordNet (r) 3.0 (2006)

actinometry
    n 1: measuring the intensity of electromagnetic radiation
         (especially of the sun's rays)

from The Collaborative International Dictionary of English v.0.48

Actinometry \Ac`ti*nom"e*try\, n.
   1. The measurement of the force of solar radiation. --Maury.
      [1913 Webster]

   2. The measurement of the chemical or actinic energy of
      light. --Abney.
      [1913 Webster]