I saw these clouds last night and all I could think was AHHHHH!! ALIENS!! The things TV does to our brains huh? hehe
Mostly just a LOT of very fine dodging and burning inside the clouds, one layer of shadow/highlight, one pass of VP set to original/contrast (reduced opacity on this layer because it was a bit much IMO). Very little sharpening because I wanted the clouds to stay poofy. So, 2 USM passes at 50, 0.5, 0.