I’m doing a Top 10 gifs of 2012 because people like pointless arbitrary lists at the end of the year. So, I’ll say this is #10 on the Top 10 Gifs of 2012.
Each photo is 12 minutes apart, assembled with no measurements in place (obviously) with Photoshop. No exposure adjustments or color compensations.
This is a rare meteorological phenomenon called a skypunch. When people see these, they think it’s the end of the world. Ice crystals form above the high-altitude cirro-cumulo-stratus clouds, then fall downward, punching a hole in the cloud cover.