This report discusses concepts, symbols, units and nomenclature for describing the transmission of radiant flux through earth's variable density atmosphere. The geometrical concepts used in the field of photometry and radiometry are the same. A common set of symbols is proposed for use in both fields together with some terms not previously used.
Irving J. Spiro,
R. Clark Jones,
David Q. Wark,
"Symbols, Units and Nomenclature for Atmospheric Transmission," Optical Engineering 4(3), 403116 (1 March 1966). https://doi.org/10.1117/12.7971329