Why does the earth and oceans emit primarily infrared photons?

Question

Climate on earth depends a lot on infrared photons being emitted by the earth and its oceans.

I want to know why the atoms in earth elements emit infrared photons after absorbing visible light, UV light, etc.

Number 12 at: Why do electrons absorb and re-emit photons? explains a lot about capture and emission of photons in general.

However, I cannot find an explanation of why infrared photons come off the solar heated earth (and its oceans) and how in the world do the behaviors of atoms emitting photons have anything to do with temperature at all, let alone temperature to the fourth power? Do the thermal vibrations of a solid occasionally add to the energy in the electron cloud surrounding an atom to cause the emission of an infrared photon? Does the valence level of the dropping electron cloud in most earth atoms, such as silicon, nickel, aluminum, oxygen, etc. happen to correspond to the emission of an infrared photon?

Answer 1

The quantum mechanics modeling of solids and liquids, which is the composition of the earth, includes not only the atoms, but the molecules and the effect of the spill over electromagnetic potential of molecules (example) to create bound lattices and ensembles of molecules as in liquids. Also in gases the scattering interactions of molecules and incoming radiation transfers energy and momentum in specific distributions.

Do the thermal vibrations of a solid occasionally add to the energy in the electron cloud surrounding an atom to cause the emission of an infrared photon?

No, thermal vibrations are vibrations of the lattice and the spill over field from the atoms and molecules is very low energy, in the case of the earth going into the infrared energies.

Does the valence level of the dropping electron cloud in most earth atoms, such as silicon, nickel, aluminum, oxygen, etc. happen to correspond to the emission of an infrared photon?

Some might, but infrared comes primarily from lattice energy changes which are very soft.

These are described by the black body radiation and connected with temperature, as here . Black body radiation is one of the main reasons quantum mechanics had to be invented. So it all depends on temperature, and the temperatures of the earth peak at the infrared frequencies.