Some scientists might have no clue. You'll want to find ones that do. I assure you not all scientists are clueless on the subject.
I can stick my multimeter probes on my body, on my clothes, in my hair, on the door, the doorknob, my slippers, the carpet and show zero volts all over the place. Yet when I rub my pink bunny slippers on the carpet and touch that doorknob.....ouch! What happened? Basic simple to explain static electricity happened, that's what.
We built up enough charge to break down the hold those little nucular heathens have on their outer electron shells and zap...they jumped the gap. Wait what? what gap?
That band gap again: (
http://en.wikipedia.org/wiki/Band_gap)
Ok so wait the air is not that hot, so it's not heat, then it must be a photon, where is the photon coming from?
Scientists just don't know....lol I'm kidding of COURSE they know....they're just not telling you....Maybe they want to sell books, maybe the scientists you read really don't know....but I can't possibly be the only one who does know.....
And I do know....so....
The photon is a virtual photon that comes from the electric field. The electric field comes from the massive potential difference (EMF, voltage) between ground and a cloud with lots of static charge built up in it, or 2 clouds with a massive difference in charge buildup.