There’s a new cloud in the sky — and citizens helped find it

When cloud watchers first spotted the distinctive, choppy waves blanketing the sky, they did what any fascinated cloud watcher would do: crane their necks skyward and take a picture.

Now, after at least a decade of inspiring photographs and wonder, the cloud pattern has also inspired an update to the international classification of clouds, the World Meteorological Organization announced Thursday — a new designation called asperitas, drawn from the Latin for “roughness.”

The new cloud feature, which is found in patchy or occasionally rounded Altocumulus clouds, is now included in the International Cloud Atlas, which sets the international standard for how clouds are classified. It distinguishes clouds based on their shape and altitude, and each of the ten major groups of clouds have additional variations among which asperitas now resides.

“Asperitas was first identified with the help of citizen science, enabled by modern technology. When Cloud Appreciation Society members send us photographs of dramatic skies from around the world, it is possible to spot patterns,” Cloud Appreciation Society founder Gavin Pretor-Pinney said in a press release. “This is how the proposal for a new classification came about, and we are delighted the WMO has chosen to include it in their definitive reference work for cloud classification.”

Though the current system of classifying clouds goes back further to 1802, according to the Cloud Appreciation Society, the discovery of asperitas as a distinguishing cloud feature was much more recent. Among the first photos that the Cloud Appreciation Society noticed asperitas in dated back to 2006, and a particularly gloomy day over Cedar Rapids, Iowa. But instead of ruing the weather, the cloud enthusiasts of the society noticed something different: the new wave-like feature that they then couldn’t find a name for in the existing Atlas.

Two years later, the Cloud Appreciation Society proposed adding the feature to the Atlas, based on several more photographs sent in by their membership of cloud watchers. But proposing an update wasn’t easy. The last update to the manual of clouds and weather phenomena had happened in 1987, before the Internet and smartphones had changed the way people live (and observe their local weather patterns).

So when the WMO announced the update on World Meteorological Day, those cloud watchers rejoiced.

The update can also now be accessed by cloud fans on the web — a first for the reference which first began publishing in 1896.

In addition to asperitas, the atlas is adding a new species of cloud (volutus, which distinguishes certain clouds that look like rolls or tubes) and four other features (like tail clouds and wall clouds). The atlas update also adds some “special clouds” caused by natural events on the ground, like fires or waterfalls, and human activities like flying.

Asperitas’ inclusion in the atlas also cements its place in what WMO Secretary-General Petteri Taalas called “the single most authoritative and comprehensive reference for identifying clouds” in a press release.

“If we want to forecast weather we have to understand clouds,” Taalas added. “If we want to model the climate system we have to understand clouds. And if we want to predict the availability of water resources, we have to understand clouds.”

This story was originally published March 24, 2017 at 7:58 AM with the headline "There’s a new cloud in the sky — and citizens helped find it."