Growing up in the county as the daughter of a pilot, I learned a lot about clouds and the weather. I can still hear my dad's voice.... "Sweetie, when you become old enough to fly, avoid the cumulonimbus clouds. Never fly into one of these...think of them as concrete."
I couldn't get a good pic of the whole thing. The rest of the sky was a beautiful blue, the cloud looked like a giant space ship. :)