|click on the picture for a larger view!|
These unusual Kelvin-Helmholtz wave clouds are formed when two different layers of air move past one another at different speeds. They're rarely seen because they usually only last for a minute or two before dissolving.
In fact, in the minute or so it took me to grab my camera, they had already unfurled from tight curls to these gently undulating waves.
I think they look like Dr. Seuss birds, don't you?
I wonder if these swirly clouds were the inspiration behind Van Gogh's Starry Night?