I know this is getting picky, but what are the lines going through the clouds? This looks like it was taken though a window. Is it reflection of the lighting inside? Whatever it is, it's kind of distracting from the overall "untouched by man" theme. If not for them, I think this would be an excelent example of the challenge. The angle and framing/cropping are good, and the clouds are really nice as well. the color is a bit dull, and it need some contrast, but it's still a pretty shot. Good luck in the challenge.
I can see reflections off glass in this. The colours are muted, and the composition is awkward. I would have liked to see more of the mountains down there. The clouds alone aren't spectacular enough for an interesting photo.
Nice sky, but the haze is very distracting. Did you shoot this out of a window? I see two bars that look like florescent light fixtures and other misc. reflections, not good. 7 Swash