Bemporad's formula
From Glossary of Meteorology
A formula for the optical mass m in terms of the zenith distance z of the sun or other celestial body;
For values of z less than about 70°, Bemporad's formula can be replaced by the simpler approximate formula,
List, R. J., ed. 1951. Smithsonian Meteorological Tables. 6th rev. ed., . p. 422.
For values of z less than about 70°, Bemporad's formula can be replaced by the simpler approximate formula,
List, R. J., ed. 1951. Smithsonian Meteorological Tables. 6th rev. ed., . p. 422.