Son of low-hanging fruit   Some thunderstorms manage to generate
blue jets shooting out of their thunderheads, or  glowing red
rings and associated tentacles around 70 kilometers up.   C T R
Wilson predicted this long ago, back in the 1920s.  He had a
simple model that gets you started.  You see, you can think of
the thunderstorm, after a ground discharge,  as a vertical
dipole. Its electrical field drops as the cube of altitude.  The
threshold voltage for atmospheric breakdown is proportional to
pressure, while pressure drops exponentially with altitude: and
as everyone knows, a negative exponential drops faster than any
power.  The curves must cross.   Electrical breakdown occurs. 
Weird lightning, way above the clouds.  As I said, people
reported sprites at least a hundred years ago, and they have
probably been observed occasionally since the dawn of time.
However, they’re far easier to see if you’re above the clouds –
pilots often do.  Pilots also learned not to talk about it,
because nobody listened.   M