Photon absorbtion and reemission in water vapor

The real question:

Water vapor absorbs photons at 950nm — does that mean that it reemits a photon at 950nm later, or does it heat up, emit photons at a longer wavelength, or what?

The "I’m curious" question:

I know that in general, if a gas has an absorption line when it’s cold, it has an emission line at the same wavelength when it’s hot. And that some materials will absorb photons at some wavelength and emit longer-wave photons (i.e., florescence or under the right conditions with some materials, lasing).

Are there any general rules about what happens when a photon at a certain wavelength is absorbed? When an atom or molecule absorbs a photon and becomes excited does it ever reemit a photon at that wavelength? Never does it? It depends on the material?