Here is a photo of an unusual cloud formation shot in Birmingham, Alabama. Called a Kelvin-Helmholtz instability, the formation is caused when the wind is moving at different speeds at different altitudes, creating a shearing effect and resulting in clouds shaped like slow-moving waves across the horizon.
And who’d a thunk it, but there is a website for the Cloud Appreciation Society, which has user contributed photos of clouds from around the world and beyond.