http://apod.nasa.gov/apod/ap120723.html
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2012 July 23
Lightning Captured at 7,207 Images per Second
Video Credit & Copyright: Tom A. Warner, ZTResearch, www.weathervideoHD.TV Explanation: How fast is lightning?
Lightning, in fact, moves not only too fast for humans to see, but so fast that humans can’t even tell which direction it is moving. The above
lightning stroke did not move too fast, however, for
this extremely high time resolution video to resolve. Tracking at an incredible 7,207 frames per second, actual time can be seen progressing at the video bottom. The above
lightning bolt starts with many simultaneously creating ionized channels branching out from an negatively charged pool of
electrons and
ions that has somehow been created by drafts and collisions in a
rain cloud. About 0.015 seconds after appearing — which takes about 3 seconds in the above time-lapse video — one of the meandering charge leaders
makes contact with a suddenly appearing positive spike moving up from the ground and an ionized channel of air is created that instantly acts like a wire. Immediately afterwards, this hot channel pulses with a tremendous amount of charges shooting back and forth between the cloud and the ground, creating a
dangerous explosion that is later
heard as thunder. Much remains unknown about
lightning, however, including details of the
mechanism that separates charges.