How to discover a new type of cloud

Asperatus cloud formation, by Don Sanderson

Back in 2006, Don Anderson snapped this picture of an amazing cloud formation. He uploaded it the web site of the “Cloud Appreciation Society”, a deliciously-named organization founded 2004.

But it turns out that Anderson wasn’t alone. Other members of the Society were discovering, all around the world, this same formation — where the clouds cut deep, jagged valleys across the sky, producing a freaky, end-of-the-world look. These clouds weren’t new, of course; they’ve been occurring for aeons, and people have probably been taking pictures of them for aeons too. But before the Cloud Appreciation Society started up in 2004, they didn’t have anywhere to share them.

Now they did. Before long, submissions of this odd formation were coming in from all around the US, Europe, and Canada, including gorgeous shots like these:

As the founder of the Cloud Appreciation Society, Gavin Pretor-Pinney, saw these submissions trickle in, he realized his group had collectively stumbled onto something interesting: A new type of cloud.

This formation wasn’t listed in the International Cloud Atlas, published by the World Meteorological Organization since 1896. So Pretor-Pinney devised a name for this cloud — “asperatus”, derived from “a passage in Virgil describing a roughened sea”. He’s been working for years to get it accepted into the next edition of the Atlas. In this week’s New York Times Magazine, there’s a superb piece by Jon Mooallem detailing the whole story.

The discovery of asperatus clouds is a lovely side-effect of what, in my book, I call “public thinking”: When disparate folks publish their observations online, they quickly discover the other people who share their seemingly niche obsession. As Mooallem writes:

Pretor-Pinney assumed that this phenomenon was so rare that, until now, no one had recognized it as a repeating form and given it a name. “As the hub of this network, a network of people who are sky-aware,” he said, “it’s easier to spot patterns that, perhaps, weren’t so easy to spot in the past.”

Today’s wave of “citizen science” is, of course, predicated on precisely this epiphany: The number of everyday folks interested in the natural world massively outnumber the scientist population, so why not harness them? There are now organizations set up have citizens classify galaxies, count hummingbirds, report coyote sightings, and parse reports of plankton.

But what charms me about the story of asperatus is that the discovery was unintentional.

Pretor-Pinney didn’t create the Cloud Appreciation Society specifically so he could identify a new cloud formation. No, he created it because clouds are rad; because staring up the darkening sky brings deep aesthetic delight. (As Mooallem notes, this is the rare group of people who, when their annual convention takes place on a crystal-blue day of gorgeous weather, are utterly crushed.) As goes the koan of open-source software, “given enough eyeballs, all bugs are shallow”. Collect together enough people intrigued with some corner of culture or science or history, let them talk long enough, and odds are they’ll stumble into something the world hasn’t yet seen. Inquiry is often sparked by joy.

BTW, my single favorite picture of asperatus is this one, taken by Elaine Patrick. The sky looks so tangible!

Asperatus cloud formation by Elaine Patrick

Asperatus cloud formation, by Elaine Patrick


4 thoughts on “How to discover a new type of cloud

    1. Clive Post author

      I’ve been reading about him ever since Ken mentioned him in the comment below!

      He’s really fascinating. I hadn’t realized there was a subculture of folks devoted to “naked eye” astronomy, though it makes sense. (It reminds me of free diving: The pleasures, and bragging rights, that come from eschewing the usual technological props.)

      Also, holy moses, Horkheimer’s web site! ( It is FABULOUS. It appears to be been left utterly unmolested by any update since the turn of the millenium, and thus is an unreconstructed example of what I like to call “High Geocities”. There’s even a spinning “@” sign animated gif, which will probably continue in its ceaseless rotation until the sun explodes.

  1. Ken Knudson

    As Jack Horkheimer used to say, “Keep looking up!” He was talking about the stars, not clouds, but I’m sure he wouldn’t mind if the Cloud Appreciation Society used his tagline. I miss that guy…

    1. Clive Post author

      You know, I don’t think I’d heard of him before! He probably wasn’t on the air up in Canada when I was a kid.

      I do remember seeing all the famous Carl Sagan shows, though; they were syndicated by the CBC. *Billions and billions* of stars …

      … with, yes, all those clouds in the way.


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