As phenomena go, ball lightning is one of those things which has always fascinated me. It was said that Tesla could summon a ball of light[1], no one has ever been able to reproduce that feat. That in itself has got to be pretty cool.
I like the idea of a the microwave bubble (or even just an RF bubble). We know that ionized air reflects radio waves (ask any amateur who has bounced off the ionosphere for an over the horizon signal) so I can imagine that a 'ball' of ionized air would reflect any radiowaves that were inside of it with energy leaking out in the form of light. But how to do that with Tesla era equipment? Good question.
[1] "I never saw fireballs, but as a compensation for my disappointment I succeeded later in determining the mode of their formation and producing them artificially.
" --
http://www.bibliotecapleyades.net/tesla/esp_tesla_20.htm
You can make something akin to ball lightning in your (friend's) home microwave:
Get a birthday candle, melt some of it onto a small plate, then stick it on the plate. Put the plate in the microwave. Turn the microwave on high for about 1-2 minutes.
Again - don't do this at home with a microwave you care about...
"akin" isn't really much use. To read what visitors to Tesla's laboratory saw it was much like something imagined for a book on magic where a magician conjures a ball of light to illuminate the room and follow around the magician.
It's fun to think about because many many people saw him do it and yet no one has figured out how he did it, and not for lack of trying. Its like the "Fermat's Theorem" of physics phenomena as far as I'm concerned.
Now that I've got a couple of software defined radios (SDRs) that can generate microwaves on demand with an arbitrary modulation, I expect there might be some fun experiments to do here.
These are very likely long exposures that captured groundings over time. It'd look much less impressive in person, and more in line with what you've seen reproduced.
The video in this article comes as a relief. When I was a teenager, sitting in the backseat of my parents car I saw something exactly like that. Nobody else saw it; there were no reports of a meteorite, and I always worried that it was a dream I was unable to separate from reality. I am sure now that I've seen ball lightning.
Anecdotally, I've seen something sort of similar too. When I was younger, I recall a massive electrical storm that came across our house. The tree against the wall got struck, splitting it in half.
I was in the hallway when it happened, and immediately tripped the power out. Though directly after the initial flash that illuminated the whole house, there was this weird echoey persistence of light and sound, and both myself and my Dad could see this ball of light jumping between the light sockets along the roof for several seconds. Sort of the same effect you see when you catch a glimpse of the sun, then blink after and see the persistence of the suns shape in your field of vision. About half a second after each 'jump' it made a really loud crackling sound, and each globe was toast afterwards.
It was really strange, and Dad put it down to ball lightning. Though it's not something we often discuss because of the uncertainty around the topic in general. I often dismiss it as one of those 'maybe I remember it wrong because I was so young'.
I'm pretty convinced it's a firefly after watching the video frame by frame. Go to the YT video, set it 1080p and pause at 36s. Then go frame by frame (use ',' and '.' to go back/forth by a single frame) and you can see it appear as a dark blob, that comes down, eventually lighting up, then contrary to your point 3 it actually goes in front of the trees.
I did go frame by frame myself earlier. The fact that it starts as a dark blob is pretty good evidence for it being a firefly, and I think I saw it earlier as part of the dramatic increase in diameter, but I can't see it that way right now.
For me it's hard to tell whether it "actually" goes in front of or behind the trees. I was thinking if it were bright enough it could fade as it descends behind the treeline. It would be a rather large firefly if it went behind the trees, though.
There's still debate over how airplane wings work and how bicycles balance too.
It fascinates me that some problems seem to be easier to solve than others. Are they actually easier, or is it that they've had more work put into solving them either because they're more interesting or because a powerful group needed them solved ?
We don't know how it actually happens. The mechanisms we know for building up charge separation in clouds should not produce fields strong enough to initiate lighting, and measurements back that up. The fields are too weak by an order of magnitude.
We don't know if there is some other mechanism that produces stronger fields locally that gets lightning started, or if something lowers the required field strength, or maybe something else.
Here is a recent article on a new mechanism that may have something to do with it, and that casts doubt on a theory that has been popular for a couple decades [1].
Here's another article that mentions that, and mentions some of the other lightning mysteries [2].
I'm glad someone did a good write-up of the research. I read through the paper one afternoon and it was super dense and I couldn't make heads or tails of the math. It is a really cool phenomenon!
This isn't new. In fact I'm pretty sure I remember reading an article referenced here at least a year ago. Headline should be "A New Article on the now current accepted theory on Ball Lightning".
There is a phenomenon in Norway that might be related to this that I find very interesting. The research here is called Project Hessdalen. See http://www.hessdalen.org/index_e.shtml
Unfortunately, the phenomenon has been victim of a lot of ridicule, linking it to the ufo fringe. Potentially, however, understanding this could be a key to unknown sources of energy. I mean this in a scientific way.
I like the idea of a the microwave bubble (or even just an RF bubble). We know that ionized air reflects radio waves (ask any amateur who has bounced off the ionosphere for an over the horizon signal) so I can imagine that a 'ball' of ionized air would reflect any radiowaves that were inside of it with energy leaking out in the form of light. But how to do that with Tesla era equipment? Good question.
[1] "I never saw fireballs, but as a compensation for my disappointment I succeeded later in determining the mode of their formation and producing them artificially. " -- http://www.bibliotecapleyades.net/tesla/esp_tesla_20.htm