Sprites are an incredible phenomenon and another darn good reason not to overfly the core of a thunderstorm.
Wiki:
Optical imaging using a 10,000 frames per second high speed camera shows that sprites are actually clusters of small, decameter-sized (10–100 m, 30–300 ft) balls of ionization that are launched at an altitude of about 80 km and then move downward at speeds of up to ten percent the speed of light, followed a few milliseconds later by a separate set of upward moving balls of ionization.[6] Sprites may be horizontally displaced by up to 50 km from the location of the underlying lightning strike, with a time delay following the lightning that is typically a few milliseconds, but on rare occasions may be up to 100 milliseconds.
I suggested in the early 90s that the entire core of a discharge might be lasing. The collapsing energy is easily able to make use of the very crude lens formed by the plasma-line structure.