Rare wave-like cloud formations spotted in the Midwest
Known as asperitas, the cloud structures form on the bottom of a cloud, creating a wave-like ceiling when viewed from below.
Asperitas clouds form over Hubertus, WI
Asperitas clouds form over Hubertus, Wisconsin on Wednesday. (Credit: @EileenWorman/Twitter)
Images taken in Wisconsin and Illinois capture rare cloud formations that resemble rippling ocean waves.
Known as asperitas, the cloud structures form on the bottom of a cloud, creating a wave-like ceiling when viewed from below, according to the UK Met Office.
The process that forms asperitas clouds is still unknown. Several theories abound, including one that involves mammatus clouds and changing wind direction and height, the UK Met Office said.
"Although they appear dark and storm-like, they tend to dissipate without a storm forming," the National Weather Service said. "The ominous-looking clouds have been particularly common in the Plains states of the United States, often during the morning or midday hours following convective thunderstorm activity."
The cloud formation was added to the International Cloud Atlas in 2017.
In Wisconsin, asperitas were seen hovering over apartment complexes in New Berlin.
Asperitas over New Berlin, Wisconsin.
(@JamNado / Twitter / FOX Weather)
Asperitas clouds were also seen over DeKalb in northern Illinois, where they appeared in a more tight-knit fashion.
Asperitas over DeKalb, Illinois.
(@Emokwx / Twitter / FOX Weather)
About 30 miles north, near the Wisconsin-Illinois border, soft, rolling asperitas hovered over a field in Caledonia.
Asperitas just west of Caledonia, Illinois, at route 173 and I-90.
(@KasperAg35 / Twitter / FOX Weather)