This past March, several new cloud names were added to the International Cloud Atlas. These additions are the first to the Atlas in over a century.
You may have seen one of the clouds before as a thunderstorm moves through. It is called an Asperitas cloud, and it looks more like waves in a rough sea upside down.
International Cloud Atlas describes an Asperitas cloud this way:
"Well-defined, wave-like structures in the underside of the cloud; more chaotic and with less horizontal organization than the variety undulatus. Asperitas is characterized 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 the cloud can lead to dramatic visual effects."
The wavy motion is produced by the winds at the cloud level changing speed and direction with height and the motion of air becomes visible in the cloud.
You can see these clouds ahead of a thunderstorm right after the leading gust front has blown through the area.
So the next time a thunderstorm approaches, get to a safe place and look skyward to try and catch the beautiful Asperatis clouds.