fluence, F,Ψ, H 0 in atmospheric chemistry

At a given point in space, the radiant energy incident on a small sphere divided by the cross-sectional area of that sphere. It is used in photochemistry to specify the energy delivered in a given time interval (for instance by a laser pulse).
See also: dose, photon fluence
ISO 31-5: 1992 (Quantities and Units - Part 5: Electricity and Magnetism.)
See also:
PAC, 1996, 68, 2223 (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2242