Atmospheric Attenuation

a reduction in the intensity of electromagnetic radiation in the earth’s atmosphere as a result of the absorption and scattering of the radiation.

Solar radiation is absorbed primarily by water vapor and ozone and is scattered by molecules of air and aerosols. Scattering plays the main role in the atmospheric attenuation of solar radiation. The attenuation of long-wavelength terrestrial radiation from the earth’s surface, from the air, and from clouds also occurs in the atmosphere.

Atmospheric extinction, or the attenuation of starlight in the atmosphere, is especially important to take into account in astronomical observations. The intensity of atmospheric extinction depends both on the wavelength used for an observation and on the zenith distance of the celestial body being observed. The same celestial body appears three stellar magnitudes fainter at the horizon than at the zenith.