I just can't stop studying cumulus clouds. This time it's a wall of cumulus or a monster cumulus.
Render settings similar to usual:
Q:0.8
AA: Narrow 5x
Atmo: 60 Clouds: 600
GI: 1/3 SS
Link for a bigger picture (click "Download") --> http://porcupinefloyd.deviantart.com/art/Monster-108932529
Seems to need more small scale details.. A good formation otherwise.