Figure 1: Spectral solar irradiance outside the atmosphere and on the surface of the Earth at sea level,
in both cases with the sun at the zenith and for a mean Earth-sun distance. Shaded areas indicate absorption before reaching the surface of the Earth at sea level due to the atmospheric constituents shown (from [1], [58], adapted from [59]).
For comparison of Figures 1 and 3: 1000 W · m–2 · µm–1 = 100 mW · cm–2 · µm–1 = 1 mW · cm–2 · (10 nm)–1