Undulatus asperatus (or alternately, asperatus) is a cloud formation, proposed in 2009 as a separate cloud classification by the founder of the Cloud Appreciation Society. If successful it will be the first cloud formation added since cirrus intortus in 1951 to the International Cloud Atlas of the World Meteorological Organization. The name translates approximately as “roughened or agitated waves”.

Topless activist Kaila J. walks through the rain following a “Free the Nipple” demonstration in Hampton Beach, New Hampshire August 23, 2015. (Photo by Brian Snyder/Reuters)

Some wave over the rainbow – a splash of colour is captured in spray over the sea wall at Totland Bay on the Isle of Wight off the south coast of England on February 16, 2022. (Photo by Jamie Russell/Bournemouth News)

A crowd of people gathered at the seaside of Udaipur, Digha, India before a cloud burst of rain on May 21, 2022. India Meteorological Department (IMD) has predicted that the Monsoon rain will likely arrive a week early this year due to twin cyclones, Asani and Karim. (Photo by Avishek Das/SOPA Images/LightRocket via Getty Images)

A rainstorm moves over the Atlantic Ocean after passing through Camden, Maine, at sunset, Tuesday, August 1, 2023. (Photo by Robert F. Bukaty/AP Photo)

Before sunrise there is a “Turneresque” sky over the abbey at the picturesque Wiltshire, England market town of Malmesbury on June 11, 2023. (Photo by Terry Mathews/Alamy Live News)

“Catch of the Decade”. Can you guess what happened next? Photo location: Katmai National Park, Alaska, USA. (Photo and caption by Aaron Baggenstos/National Geographic Photo Contest)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)