Air mass coefficient
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The air mass coefficient characterizes the solar spectrum after the solar radiation has traveled through the atmosphere. For a thickness lo of the atmosphere, the path length l through the atmosphere for solar radiation incident at angle θ relative to the normal to the Earth's surface is
l = lo / cos θ
The ratio l / lo is the air mass coefficient [1]. The spectrum outside the atmosphere is AM0. The spectrum on the surface of the Earth for normal incidence is AM1. A typical spectrum for moderate climates which is often used in the characterization of solar cell efficiencies is AM1.5, which corresponds to a solar zenith angle of 48o. [2]
[edit] References
- ^ Peter Würfel (2005). The Physics of Solar Cells. Weinheim: Wiley-VCH.
- ^ NREL - Reference Solar Spectral Irradiance: Air Mass 1.5
