This image is a combination of two graphs about electromagnetic radiation. The upper panel shows graphs of Planck's Law of Radiation Emission. Any substance will emit electromagnetic radiation in an amount, and centered at a wavelength, both of which depend on the temperature of the substance. For example, the sun has temperature of roughly 6000 degrees on the Kelvin grade scale and Planck's Law dictates that the wavelengths at which it emits its maximum radiation is centered on the "visible light" portion of the spectrum. Earth's surface, on the other hand, has a temperature of roughly 280-300 degrees on the Kelvin scale, and Planck's Law dictates that its wavelength of maximum radiation emission is in the infrared, centered at about 1 micron (millionth of a meter) in wavelength. The stratosphere is somehwhat cooler than earth's surface, and its Planck emission spectrum is shifted to slightly longer wavelengths.
In the bottom panel, the absorption spectrum of earth's atmosphere is shown on the same wavelength scale as the Planck radiant emission graph. The color scheme is chosen to relate to "transparency", where the lighter color relates to the degree of transparency, while the darker color relates to opacity. One may see that earth's atmosphere is highly transparent at those wavelengths corresponding to the maximum solar emission (i.e. the visible wavelengths). On the other hand, there are spectral regions of substantial degrees of atmospheric opacity in the infrared, owing to the absorption by the greenhouses gases. At longer wavelengths labeled "far infrared", the atmosphere is again highly transparent. In the microwavelength region, one may see atmospheric absorption "fingerprints" owing mostly to absorption by oxygen and water vapor.
