Infrared spectrum earths atmosphere

A second problem presented by the increase in carbon dioxide stems from its effect on the thermal balance of the earth. The sun is at a temperature of about 6000 Kelvin and emits most of its energy in the visible and near infrared portion of the spectrum. The atmosphere and the carbon dioxide are transparent to the wavelengths of this portion of spectrum. These wavelengths pass through the atmosphere and warm the surface of the earth. Because of its transparency for short wave length solar energy, carbon dioxide does not reduce the amount of energy received at the earth s surface. ... 

The air itself, being composed primarily of homonuclear diatomic molecules such as N2 and O2, does not compete because those vibrational transitions are infrared inactive. Sunlight, primarily in the visible and near-infrared region of the spectrum, warms the earths surface. As the earth heats up, it releases some of that energy as infrared radiation. Atmospheric gases absorb some of that radiation, but regions of the infrared spectrum where the... 

Farmer, C. B. Norton, R. H. (1989). A High-Resolution Atlas of the Infrared Spectrum of the Sun and the Earth Atmosphere from Space. NASA Reference Publication 1224, Vol. 11. Washington, DC NASA, Scientific and Technical Information Division. Farmer, C. B. Raper, O. F. (1986). High resolution infrared spectroscopy from space ... 

Since the atmosphere shields us from most deep ultraviolet radiation and from infrared radiation, the bulk of visible light (the solar spectrum) ranges from 350 to 750 nm. The 25,000 Frauenhofer15 "dark" lines are interruptions (in the range 295 to 1000 nm) in the continuous solar emission spectrum, due to absorption by the chemical elements present in the sun s atmosphere. Ultraviolet radiation was discovered by Ritter16 in 1801. Some radio waves do penetrate the earth s atmosphere, and they are most intense during solar storms. Infrared radiation also penetrates to some extent. 

The central role of hydroxyl radicals in atmospheric chemistry is well illustrated by examining the atmospheric cycles of methane and carbon monoxide. A quantitative assessment of both of these species was carried out in the 1920s in Belgium by Marcell Migeotte, who detected their absorption lines in the spectrum of infrared solar radiation reaching Earth s surface. 

FIGURE 20.31 Visible light from the sun strikes the earth s surface and heats it. Much energy is radiated back into space in the longer wavelength infrared region of the spectrum. Molecules in the atmosphere and in clouds can block some of this loss, keeping the lower atmosphere warmer than it would be without these molecules. 

The solar spectrum outside the Earth s atmosphere extends from about 200 nm to 2500 nm, half of the energy being concentrated in the visible part of the spectrum, 40% in the infrared, and 10% in the ultraviolet. Practically all the radiation below 295 nm is. filtered out by the atmosphere so that the solar energy reaching the Earth s surface is distributed according to the spectrum shown in Fig. 1 [1]. 

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