Actually, I thought you explained it well, other than a few odds and ends, that I wanted to try to understand too.CC said: I think that I'm bad at explaining this stuff, because I've been so deep in the theory for so long that I have long since forgotten the point of entry. So I don't know what pieces I have to supply to people so that they'll get it, the same way I do. But here's an analogy that might help.
Imagine standing on a steel deck. Now imagine that some hot, positively charged air has been manufactured. This electric charge will induce an opposite charge in any nearby conductor, and thereafter be attracted to it. Thus the positively charged air will induce a negative charge in the surface of the steel deck, and then the air will be pulled down to the deck by the electric force.
How does the body of air get a positive charge? How does positive charge in air induce negative charge on conductors, like the steel deck? If the positive air is attracted to the negative deck, why doesn't it recombine with and neutralize the deck and itself?
I can understand that part, except for what prevents charge recombination.And it doesn't take much electric force to overpower gravity, and get hot air, which ordinarily would have risen due to its buoyancy, to be held down to the deck. So you have air that has a build-up of thermal potential, which will rise if given the chance, but the electrostatic potential is offsetting the thermal potential, and holding the air down to the deck.
Is the welding machine's arc meant to be analogous to lightning? Maybe not, since you say dark discharge.Now, reach over to the welding machine next to you, grab the whip, and dial up a negative charge to the tip of the whip, and point it at the deck. If you don't dial up enough voltage to get an arc between the whip and the deck, you'll still get a flow of electrons as a dark discharge. These electrons will be attracted to the positively charged air, and they'll burrow their way through the neutrally charged air to get down to it. On arrival, the electrons will neutralize the positively charged air, which will then be free to ascend, due to the buoyancy of hot air. Now you have an updraft.
But then does there need to be sustained lightning or dark discharge?Air will then converge along the deck toward [the base? of] the updraft, to replace the air that rose. When it gets to where the electron stream is, it will get neutralized too, releasing it from its electrostatic attraction to the deck, enabling it to rise as well. So now you have a sustained updraft, and a sustained convergence of air moving horizontally across the deck.
Would trees, hills, buildings, or other obstacles cause the horizontal inflow to become asymmetrical? It sounds like the evacuated core is a lightning channel. Right? Or do dark discharges have similar channels?If the horizontal inflow to the updraft is asymmetrical, a vortex will form, so the updraft will spiral around the axis of the vortex as it rises. Interestingly, the evacuation of matter in the core of the vortex makes it a better conductor. So the electrons flowing down from the welding whip will prefer the vortex as a conduit to get to the positively charged air clinging to the deck. This enables even more current to flow, and thus even more positively charged air can get neutralized and join the updraft.
I'm not clear on the meaning of self-stabilizing here.The enhanced electric current through the vortex also generates ohmic heating, which further increases the buoyancy of the updraft in the vortex. So electric currents and fluid dynamic vortexes are mutually enhancing.
Finally, the air skidding along the deck picks up even more heat due to skin friction. So when it gets neutralized by the electric current inside the vortex, it will rise even faster.
Thus a vortex has been formed on top of the steel deck, just by the neutralization of positively charged air flowing downward, and once formed, the vortex and the electric current are self-stabilizing.
If you start with formation of the body of positive air, then it starts with charge separation. Doesn't it?This will continue until the supply of positively charged air runs out, or the supply of electrons to the welding whip is shut off. And notice that we didn't need any sort of updraft over our heads to kick this thing off -- it all started just with charge recombination.
Is the electric current mostly lightning, or dark current or something?This is analogous to tornadoes. There doesn't have to be a large rotating updraft inside the thunderstorm for a tornado to form, but the electric current inside the tornado was there every time somebody tried to measure it. And the current isn't going into the ground, or it would have left a mark, and which has never been found. So the current is going into the air itself. And the smell of ionized air is distinctive, and which has been reported frequently in the tornadic inflow. So that's positively charged air flowing toward a neutralizing current inside the vortex.
What I said previously about moving air having lower pressure than stationary air may apply to hot air too, since hot air is in motion more so than cooler air, though the motion is internal.