As I was digging trough my photography Archive, I've found a very interesting shot. The image is 2 years old, I remember a heavy summer rain that day and at sunset as the sky cleared out this very interesting cloud formation formed. I've never seen anything like this, It's pure coincidence, luckily the camera was there to take the shot. The image went trough some very basic post processing.
http://i.imgur.com/vAI4N5P.jpg
As you can see the cloud formation really looks like a "atomic cloud" or a cloud after a big explosion. But there was no big explosion, it's a pure random cloud formation. The one below has heavy contrast applied, it looks even more dramatic.
http://i.imgur.com/gAvPjw1.jpg