Dear Judge Alsup: The TL:DR

Gingerbaker asked for the TL:DR for the good Judge Alsup.  Eli had already written it over at Real Climate, but deep in the comments so here it is

Eli Rabett explains it all about question 2, whether N2 and O2 play a role in the greenhouse effect.

A three parter with some TL:DRs below

A bit on observations and spectroscopy: http://rabett.blogspot.com/2018/03/dear-judge-alsop-spectroscopic-basis.html showing that the collision free absorption of O2 and N2 can be ignored. Just too small

A discussion about the physics of molecular spectroscopy: http://rabett.blogspot.com/2018/03/dear-judge-alsop-quantum-interlude.html  Shifts the balance from the qm selection rules to how molecules interact with electromagnetic radiation (e.g. IR or light). Discusses how changes in charge distributions during transitions determines whether photons are absorbed or emitted. Makes contact with electromagnetic antenna theory, eg electric dipole allowed transitions w. dipole antennas, etc. 

Eli figured the good Judge, having been a ham radio operator should grok that.

Collisional effects http://rabett.blogspot.com/2018/03/dear-judge-alsop-putting-on-pressure.html
Starting from the quantum interlude discusses (much paw-waving) how collisional induction of electric dipoles drives continuum absorptions for N2, O2, CO2 and H2O (by implication, need to add a paragraph, the water vapor continuum being an important part of the greenhouse effect, of course the concentration of water vapor in the atmosphere is dialed in on average by the non-condensible greenhouse gases.)

There were a couple of open questions in the discussion which the Bunny will get around to next week.  Hope that helps.