I can't help but smile everytime I see these things. My kids love to call them cloud makers. When we fly and see them looking down from the plane we always make sure to point them out. It is simple things like this that make me smile from the pleasure of having my kids with me.
"Clouds may come, but clouds must go,
And they have a silver lining,
For beyond them all, you know,
The sun or moon is shining."