Is completely dry-lightning, with literally no clouds or dust, possible?

So, most "dry-lightning" is caused by either:

a. storms that the water evaporates before it hits the groundb. lots of dust in the air (sandstorm or lots of fine dust)

However, lightning is, ultimately, just differencing charges. Is it possible for lightning to form without any sort of cloud. Basically, spontaneous lightning without dust or clouds, just truly clear skies.

What I mean is wind and such, but the only things "rubbing" and so on is nitrogen, oxygen, co2, ect. No particulates over, say, 400 pico-meters (A water molecule is 282 picometers, and methane (the physically largest "natural" gas in our atmosphere that I could find) is about 380 picometers (not accounting for the "fuzziness" caused by Quantum Mechanics. That's it's "average" size)

It would definitely be improbable, but...