Photos are circulating on social media of a “new” kind of cloud called the undulatus aperatus, which roughly translates from the Latin to “rough waves” or “agitated waves”. These clouds are beautiful in their own special way – they look like something from a science fiction movie or out of a nightmare. The popularity of the photos prompted a couple of questions from readers: are they really new and who decides on cloud names?
To answer the first question, no, these are not new clouds. Just like all clouds, I’m sure they’ve been around since the earth’s atmosphere first took shape as we currently know it. As our technology has improved over the years, so has our increased ability to share photos of clouds and study when these clouds form. An argument has been made in recent years for creating a new classification of cloud for this type.
The clouds are similar to mammatus clouds in that they seem to hang down from an angry sky. However, mammatus clouds are generally associated with supercell thunderstorms, while undulatus asperatus tend to turn up after storms have passed. They are often reported over the plain states of the US, but have been witnessed in other parts of the world, too.
So, who gives clouds their names? The official word on cloud naming comes from the World Meteorological Organization (WMO), but they have not confirmed this new cloud type nor conferred its name. A different group, The Cloud Appreciation Society, first coined the phrase undulatus asperatus and is awaiting word from the WMO on whether it will be added to The International Cloud Atlas. The WMO requires a study of cloud formations in order to understand the atmospheric conditions that create them. Once they are sure that this is truly a new type of cloud, they can add the species to the book.
By the way, no new cloud type has been added since 1951, and if you look for a copy of The International Cloud Atlas on Amazon, you won’t find it. It was originally printed in 1975, and is currently out of print and considered a rare book. Soon, we might even consider it truly outdated.
Mammatus clouds over Shakopee, Minnesota, photograph by Niki Morock.
Undulatus asperatus over Cedar Rapids, Iowa, photograph by Jane Wiggins and published by National Geographic.