Driving northwest on Interstate 70 on a clear Sunday morning in Maryland, magnificent clouds resembling ocean waves in the sky towered over mountain ridge tops.
They’re seen much more frequently in the Western United States — especially in environments characterized by strong winds aloft and rising channels of instability off the ground. As the instability channel ascends, it is pushed over by the strong winds above, spinning up eddies.
In this case, the Catoctin Mountains helped force air flowing in from the west to rise through a process known as orographic lift. Some pockets of instability developed as the sun heated the ground and rose into colder air aloft.
Weather balloon data from Dulles International Airport on Sunday morning presented a textbook setup for these clouds. It revealed:
- An unstable layer just above the ground — encouraging the air to rise and condense into clouds.
- Strong westerly winds about a mile high over top the mountains where the clouds ascended.
- A stable layer just above the clouds, which caused the forming wave cloud to collapse, much like an ocean wave crashing into the shore.
Gorgeous examples of these wave clouds were photographed in Wyoming’s Bighorn mountains in December 2022, and in Breckenridge, Colo., in 2015.
Read more about Kelvin-Helmholtz wave clouds
