This was an incredibly fortunate shot. I captured:
1. View of Half Dome in Yosemite
2. During a lightning storm
3. While there were people halfway up Half Dome camping on the wall (that's what the white light halfway up the rock is)
4. While there were people walking around way down below (that's what the white light from the headlamp down below is).
This image has gathered over 1,000,000 views on Imgur, mostly through Reddit's EarthPorn subreddit.