We traveled from the Black Hills to Badlands NM today. Rain was the order of the day and while we were able to outrun the storm on the way east, it soon caught up to us and made the formations pretty drab. The exception was this fantastic sunset taken near the Panoramic Overlook. A tripod-mounted Canon Rebel T2i (1.6X crop factor) plus a 400mm (equivalent of 640mm) was used to zoom in to this light show. This is unaltered right from the camera. What do the cloud formations remind you of?