“Undulatus asperatus cloud formations are so rare that they were not proposed as a separate cloud classification until 2009. The Cloud Appreciation Society suggested the name asperatus, as the word comes from the Latin verb ‘aspero’, meaning to make rough. It is thought that asperatus clouds’ choppy undersides may be due to strong winds causing disruption in previously stable layers of warm and cold air.
Graeme Anderson, an MSc student at the Department of Meteorology, Reading University, studied weather records and used a computer model to simulate asperatus clouds. In doing so, Graeme found that the clouds form in the sort of conditions that produce mamma (mammatus) clouds; asperatus clouds form when the winds up at the cloud level cause the cloud to shear into wave-like forms known as undulatus.
More common in the plains of the United States (try Iowa), asperatus clouds are at their weird and swirly best during the morning or midday hours after a thunderstorm.
-Jean ” – My Comments : Funky.