Wednesday morning brought increasing low cloudiness across the KXAN viewing area, but it was the formations those clouds were creating that had many folks grabbing their cameras and snapping photos. So why were the clouds taking on such a “wavy” shape?
The cloud formation many witnessed is called “asperitus” or “undulatus asperatus,” which means “agitated waves.” This “undulation” or wave-like motion in the atmosphere is created by ocean-like waves of air moving horizontally, meeting up with a deck of developing low clouds. And voilà…you’ve got waves in the sky!
The cloud formations only recently received their own designation in the International Cloud Atlas. Here’s what the World Meteorological Organization wrote about them:
Most public interest has focused on a proposal by the Cloud Appreciation Society, based in the UK, to recognize the so-called “asperitas cloud (Latin for roughness). The international Task Team defined this as “well-defined, wavelike structures in the underside of the cloud, more chaotic and with less horizontal organization than undulatus. It is characterised by localized waves in the cloud base, either smooth or dappled with smaller features, sometimes descending into sharp points, as if viewing a roughened sea surface from below. Varying levels of illumination and thickness of cloud can lead to dramatic visual effects.”
Undulatus already exists as a cloud variety, the third level of classification, which is generally associated with stratiform clouds. The Task Team has proposed that asperitas (note spelling: after the Latin noun meaning roughness) be included as a new supplementary feature, and has selected an image for inclusion in the new Atlas, based on a competition by the Cloud Appreciation Society.