The range of wavelengths within which energy is absorbed by a substance. Atmospheric absorption of electromagnetic energy is shown in Figure E-11.
FIG. E-11. Electromagnetic spectrum. Designation of portions of the electromagnetic spectrum. The blackened areas in the right-hand graph show attenuation caused by atmospheric absorption. The window in the absorption spectrum at V is visible light and window T is the thermal infrared window. In terms of energy, 10–6 m wavelength=1 eV; 10–12 m=1 keV; 1 m=1 meV. (after Reeves et al., 1975, 54.)