Say you're in an ascending airplane as your 10 year-old son asks you: "Dad, why are these clouds wavy?" Now, say you know a little about gravity waves and the formation of wavy clouds(Maybe I should be linking to As instead? Are these wiki pages basically talking about the same thing?). How would you go about explaining it to your son?
PS. I'm looking for a simple and fluid explanation that would be able to give some intuition for the phenomena.