This site has some awesome pictures from nature, as a cloud spotter and geographer this is a particularly interesting site. The site explains "The clouds are Nature’s poetry – sometimes spoken in a whisper, sometimes roared with all her might" - what an amazing thought. I particularly like the cloud of the month (July 05!) feature!
My four year old studying weather said clouds are like a blanket which keeps the land warm, if there are no clouds it's colder. What a cute explanation.