Sprites

I was driving home from work after dark several years ago and watching the tops of some thunderheads directly in front of me. They were too far away to hear any thunder and I was only seeing the cloud tops, probably over Georgia. The lightning was lighting up the anvil and overshooting tops quite nicely and at one point I saw a vertical flash of light over the clouds. I couldn't imagine what it was. Only later I found out about sprites.

This is a great documentary with some super-slow motion captures of sprites. Mesmerizing.