Spectroscopy concerns
the absorption, emission,
and scattering of
electromagnetic radiation,
by atoms and molecules.
Visible electromagnetic
radiation is called light,
although the terms "light",
"radiation", and
"electromagnetic
radiation" can be used
interchangeably.
Molecular spectroscopy
involves the absorption
and emission of
electromagnetic
photons by molecules.
In the high atmosphere
(at low pressure) molecules
exhibit absorption in narrow
spectral bands (wavelengths).
In the lower atmosphere,
the pressure and temperature
is higher, and the spectral
peaks broaden.
Photons may be emitted
anytime molecules are in
an excited state, and may go
in any direction.
The physics is complex,
not simple, and the general
climate models fail to capture
what is physically occurring
in the atmosphere with the
changing greenhouse gases.
Water vapor is the dominant
greenhouse gas, and is not
properly modeled.
