Out of thin air: is this the world's newest type of cloud?

One man's quest to find scientific recognition for the menacing undulatus asperatus


Ten years ago, Gavin Pretor-Pinney decided to rebrand clouds, or what he likes to refer to as the “patron goddesses of idle fellows.” For too long, clouds had been co-opted by bleak expressions like “head in the clouds” and “under a cloud”; dismissed as stains on otherwise beautiful blue skies; and maligned as harbingers of crummy weather and bummer vibes. Pretor-Pinney wanted to change all that.

In 2004, the author, graphic designer, and former absinthe importer gave a talk at a literary festival in Cornwall, England in defense of clouds. On a whim, he called it The Inaugural Lecture of the Cloud Appreciation Society, though no such society existed. The talk drew unexpected attention from festival goers and early in 2005, Pretor-Pinney decided to bring the fictional society to life. In its manifesto, the Society declares that “we believe that clouds are unjustly maligned and that life would be immeasurably poorer without them.” A decade on, the organization boasts a lively online community, over 56,000 Facebook followers, and tens of thousands of members across almost 100 countries around the world.

The first addition to the cloud classification system in half a century

One of the Cloud Appreciation Society website’s most popular features is an expansive photo gallery where anyone can submit, say, an altocumulus floccus gracing the sky over Cabbagehall, Fife, Scotland, a wispy cirrus formation over Nova Scotia, Canada, or a menacing thunderstorm over Maryville, Tennessee. The section takes itself as seriously as the rest of the organization, which is to say not very — one of the major branches of the gallery is dedicated to "clouds that look like things," which includes seahorses, ghosts, cyclists, and at least one pterodactyl. The majority of the clouds on display are easily recognizable varieties: featherlike cirrus clouds and big, photogenic cumulus clouds.

But soon after launching the site, Pretor-Pinney received a couple pictures that didn’t quite fit into existing classifications. One image, taken from the 12th floor of an office building in Cedar Rapids, Iowa, looked positively apocalyptic — a violent and undulating thing menacing the city skyline. "They struck me as being rather different from the normal undulates clouds," Pretor-Pinney says, referring to clouds with a wave-like formation. "They were more turbulent, more confused — as if you were underneath the water looking up toward the surface when the sea is particularly disturbed and chaotic." Every six months or so, Pretor-Pinney says, a similar photo would come into his mailbox. In time, he came to wonder if there was a case to be made for a brand-new cloud type — the first addition to the cloud classification system in half a century.


Credit: Louisa Price, Location: Colchester, Essex, UK

In the winter of 1803, a British pharmacist named Luke Howard presented a paper titled "On The Modification of Clouds," in which he set out four primary cloud classifications: the fuzzy cirrus, the popcorn-like cumulus, the expansive stratus, and the water-logged Nimbus. Over the next century, those terms were honed and expanded on and by the late 19th century, multiple "cloud atlases" had emerged in hopes of codifying nature’s most ephemeral element. But all these were superseded by the mammoth International Cloud Atlas, published in 1896, which quickly became the global standard for cloud identification. The Cloud Atlas cemented into place four levels of classification. In order from most to least important, these are genre, species, varieties, and lastly, supplementary features and accessory clouds.

"Cloud atlases" emerged in hopes of codifying nature’s most ephemeral element

Numerous editions of the International Cloud Atlas (now overseen by the World Meteorological Organization) have been published over the decades, though the pace has slowed down drastically as fewer and fewer adjustments need to be made. The last edition was published in 1975, and with its colorful plates it is a beautiful and much sought-after commodity — copies can go for thousands of dollars. If Pretor-Pinney’s new cloud had any hope of finding any legitimacy in the world, it would have to find a way into the pages of the International Cloud Atlas.

Fortunately, the World Meteorological Organization is currently in the process of preparing the first new edition of The International Cloud Atlas in four decades. Finally, the Atlas will be available online — the clouds are coming to the cloud.


Credit: Gary McArthur, Location: Burnie, Tasmania, Australia

To name is to conjure into existence, so before Pretor-Pinney could propose a new cloud variation, he called a cousin, a latin teacher, who suggested the verb aspero, used by Virgil to describe a roughened sea. The churning clouds in Pretor-Pinney’s photos now had a name: undulatus asperatus.

Pretor-Pinney took his cloud to England’s Royal Meteorological Society who suggested he needed scientific justification for the creation of a new cloud type. So the cloud enthusiast visited the University of Reading, where a graduate student adopted the undulatus asperatus as the subject of his final paper. In 2010, Graeme Anderson published a lengthy dissertation, "Asperatus: the Application of Cloud Classification to a Suggested New Cloud Type" in which he concluded that indeed, "there is a case for defining these formations as a new supplementary feature."

Tweaking the existing Cloud Atlas is not a decision taken lightly

Tweaking the existing Cloud Atlas — either by adding or removing variations — is not a decision taken lightly. "We don’t want to make changes; it’s a standard," says Dr. Roger Atkinson of the World Meteorological Organization. "If a standard has been properly done and well written out, it should stand the test of time and place."

Accurately identifying and observing clouds can help meteorologists fine-tune weather forecasts, better understand regional ecology and even diagnose larger shifts in the global climate. A change in definitions can have a significant and lasting impact on how, and what, gets measured. Change the name of cloud A to cloud B, and overnight all the cloud As of the world vanish into thin air.


Credit: Elaine Patrick, Location: Newtonia Missouri

But there comes a point, Dr. Atkinsons says, when the benefits of including a new classification become greater than the costs of excluding it. The WMO assigned a task team to identify the needs of a new edition of the International Cloud Atlas and one of their responsibilities was establishing the legitimacy of undulatus asperatus — among a few other new varieties. In November 2013, that task team formulated a definition of the asperatus cloud: "A formation made up of well-defined, wavelike structures in the underside of the cloud, more chaotic and with less horizontal organization than undulatus. Asperatus 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."

"By naming things around us, it focuses our attention."

The task team also recommended that the asperatus be included in the forthcoming edition of the International Cloud Atlas, though the ultimate decision lies with the WMO’s larger commission body. The chances of Pretor-Pinney’s cloud coming to life, says Dr. Atkinson, is "very high, but we cannot be certain."

"Whether it’s going to be called asperatus is another matter," says Dr. Atkinson. "We need to receive advice from a proper latin scholar."

"If there is a better latin term, of course, I’m all ears," says Pretor-Pinney. For the cloud connoisseur the inclusion of the asperatus into the International Cloud Atlas would be a crowning accomplishment of what he terms "the democratization of science observation enabled by the internet." But more than that, it would give the public a reason to look up.

"By naming things around us, it focuses our attention," he says. "When you know the names of different butterflies, you start to seeing them and paying attention to them. It’s the same with clouds. The motivation is to keep people engaged with the sky — paying attention to clouds and thinking of them as a beautiful and fascinating part of our surroundings."

Lead photo by Kent Burgess, Location: St. Louis, Missouri