Spectral Flux

Spectral Flux

. The Sun’s spectral flux at the Earth plotted as a function of the wavelength in nanometers, given here in units of watts per square meter per nanometer, or W m-2 nm-1. At each wavelength, the amount of solar energy received at the Earth’s surface is less than the amount received outside the Earth’s atmosphere. The attenuation is much greater at certain wavelengths than at others owing to absorption in the Earth’s atmosphere by molecules of oxygen, O2, water, H2O, and carbon dioxide, CO2. There is a general reduction at shorter wavelengths, less than 320 nm, due to absorption by ozone, O3, molecules, and to scattering by molecules, aerosols and small particles in the atmosphere. At any given location on the Earth’s surface, the solar insolation, or power per square meter, can be obtained by integrating the spectral flux over all wavelengths.

Copyright 2010, Professor Kenneth R. Lang, Tufts University