Ah, I wondered where clouds were made. Thanks for clearing that up. ;-). Good shot, good use of rule of thirds, and perhaps oversharpened a bit. The blue sky looks pixelated, so check your Save for Web settings (but I didn't dock you any points for that).
That's what i always thought they were when i was a youngin. Great angle and use of negative space. I also like the range of values you were able to get out of the "clouds".
Of course this could be nice clean steam, but with global warming I guess that is now also considered polltion. Nice colors, good focus, good exposure.