The Carbon Quandary: Essential and Detrimental - Sustainable Design: The Science of Sustainability and Green Engineering - page 271

Figure 7.3 Patterns for heat and

light energy.

Diffraction

λ 0

Absorption

Incident Light λ 0

acts as a wave converter, receiving high-energy high-frequency radiation from the
sun and converting most of it into low-energy low-frequency heat to be radiated
back into space. In this manner, Earth maintains a balance of temperature.
To better understand this balance, the light and heat energy have to be defined
in terms of their radiation patterns, as shown in Figure 7.3. The incoming
radiation (light) wavelength has a maximum at around 0.5 nm, and almost all of it
is less than 3 nm. The heat energy spectrum (i.e., the energy reflected back into
space) has a maximum at about 10 nm, almost all of it at a wavelength higher
than 3 nm.
As both light and heat energy pass through Earth's atmosphere they encounter
the aerosols and gases surrounding Earth. These can either allow the energy to
pass through or can interrupt it by scattering or absorption. If the atoms in the
gas molecules vibrate at the same frequency as the light energy, they will absorb
the energy and not allow it to pass through. Aerosols will scatter the light and
provide a “shade” for the Earth. This phenomenon is one of the reasons that
scientists in the 1970s believed we were undergoing global cooling. That is, the
combustion of coal and other fossil fuels releases sulfate aerosols which can scatter
incoming solar radiation.