Fav! Wow! Magnificent clouds! I like Jane's idea of cropping out the sun, to see what the result is. The contrast of the clouds and the colour of the sky is amazing!
What a cool cloud! Didn't see it before but the the crop, this is outstanding. And instant fav. I might also clone out that little bush down at the bottom of the image -- the branches are a little distracting and so bare that I don't think you need it.