I think its some kind of ball lightning plasma phase thing. there is alot of weird stuff floating around the atmosphere, maybe it makes a strange particle, condensate, phase of some kind when struck by lighting that is metastable.we make weird stuff in the lab with weird conditions. i still can't explain the weird spherical spark thing that came out of the power strip when the MOV blew in that thread, but it was not grey, but the way it navigated out of the power strip without scorching everything made it seem like it has some kind of natural tendency for 'terrain following' with repulsive forces. or maybe its something weird that comes out from underseas vents from magma.
Perhaps it has something to do with nuclear testing (why this is a more recent phenomena), having to do with the decay chains of nuclear dust in the air made by testing making specific isotopes prone to catalyzing/stabilizing/forming these spheres. Also might have to do with changing the atmospheric composition with CO2 and greenhouse gas emissions, this must have a effect on refraction, ionization, etc. Just global temperature change alone maybe has some kind of spawning pool of these things form some where in the air because of stratification of different kinds, and it might be related to solar flares and particle fluxes. There is plenty of explanations other then 'we have become a sufficiently advanced civilization to attract contact'. I think its some kind of bizzaro waste product from industrial or military activity. HAARP? We also did some strange stuff like spread dust for rain formation (silver is highly conductive and normally not scattered in the atmosphere). But I believe that
1) nature can form round plasma objects, having seen one
2) billions of reactions that can be catalyzed by really weird man made shit
3) can be some kind of weird particle analogous to a WIMP (hypothetical weakly interacting massive particle), it has visual presence but very little mass and friction (super conductor version of friction). Maybe its a single atom hit by a weird particle like a strangelet (who knows what they can do) that changes nuclear force to make it act differently but still be cohesive and some how turn visible.
I think if we captured one it might have interesting results in physics.
I would suggest two aircraft fly between it and then shoot a laser through it into a receiver to measure its transmission. they should be drones because if its doing something weird with nuclear forces and light maybe it can jump between photons to induce a voltage or something strange like that. it should be treated with caution.
Also things like superconductors are being produced fairly widely right now (even if specialized and in small amounts), since this is handled often at a university level you might assume the containment is poor and some stuff does get into the air and maybe have some kind of strange interaction with lightning.