In parts of South Carolina and Georgia this morning, the sky was transformed into a turbulent gray sea filled with massive, rolling waves. The rare cloud formation that rocked the Low Country skies is known as undulatus asperatus, which means agitated wave.
The Cloud Appreciation Society proposed it be added to the official list of clouds in the International Cloud Atlas maintained by the World Meteorological Organization,but it has not yet been accepted.
“A task team assigned to the case recommended it for inclusion,” says the National Weather Service office in Columbia, South Carolina. “The next edition of the Atlas is slated for release sometime in 2015.”
Charlotte, N.C. broadcast meteorologist Brad Panovich tweeted a nice graphic illustrating how these clouds form.
Critically, an elevated layer of warm air over top a layer of cooler air (aka an inversion) is required for the wave action at cloud level. But the specifics on how the clouds develop and evolve are still under investigation.
“One theory is that when you model conditions for a mammatus cloud and then add wind, it gets features that look like Undulatus,” Graham Anderson, a scientist with the UK Met Office told the Daily Mail.
Here are some pretty incredible views – still and video – of these clouds this morning, via social media: