Relative optical air mass m--Algorithm 1.22

The value m describes the length of an oblique path through the atmosphere in comparison with the path of the sun's rays when the sun is directly overhead. The first pair of formulae gives the ratio of mean atmospheric pressure at the site to that at sea level, p/po. The third formula gives the relative air mass.

Input
Station height, h metres

Solar altitude, gs radians

Equation

Source
Kasten (1) Rogers(2).

References
  1. Kasten F and Young A T Revised optical air mass tables and approximation formula Applied Optics 28 (22) 4735-4738 (1989)
  2. Rogers G G, Souster C G and Page J K The development of an interactive computer program SUN1 for calculation of solar irradiances and daily irradiations. Department of Building Science, University of Sheffield (1978)

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