[Hunble]

I will bite:

On the other hand, electric fields always impinge on conducting spheres at right angles to their surfaces (i.e., vertically)

Why?

Is it impossible for an electrical arc to enter from an angle? And if so, why?

Of course, since you used the examples of Auroras around Io, you have an outstanding answer as to why Canada is not saturated with these craters on the ground?

Seriously, I do need to get some sleep tonight, but this is almost too fun.

[Phil V.]

Bet time for this Bonzo . . . LATER!
Hasty bannannas!!!

[DB]

Strictly replying to the sphere and right angle discharge question - The shortest path for the charge to pass would be the closest point to the sphere relative to the charged source. That would seem to be always a right angle relative to the surface of the sphere. No glancing discharges...