These are typically associated with severe thunderstorms, but they can also form in peaceful air over water/land interfaces as in this photo from Maldonado, Uruguay.
The cold air sinks, forcing the warm, moist air into a sort of atmospheric wave.
When detached from a storm, they're "roll clouds."
February 1, 2026 at 10:00 PM
These are typically associated with severe thunderstorms, but they can also form in peaceful air over water/land interfaces as in this photo from Maldonado, Uruguay.
The cold air sinks, forcing the warm, moist air into a sort of atmospheric wave.
When detached from a storm, they're "roll clouds."