ARCHIVE: 'New' cloud to have its day in the sun

This article appeared on USATODAY.COM back in June of 2015.

Asperatus — the first "new" type of cloud in decades — is about to get the recognition it deserves in the latest edition of the International Cloud Atlas, the world's top reference book for clouds.

The latest cloud species is dubbed "undulatus asperatus" — aka "agitated waves" — and looks like a surreal undulating blanket that covers part or all of the sky.

While obviously not a "new" cloud, asperatus has only been able to gain widespread attention with the advent of digital cameras, the Internet and social media.

The proposed formal definition of the cloud is: "A formation made up of well-defined, wavelike structures in the underside of the cloud ... 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 cloud can lead to dramatic visual effects."

The campaign for a new cloud was originally spurred by the Cloud Appreciation Society, a group of 30,000 weather enthusiasts based in England. Cloudspotters have been taking photos of the cloud for the past few years, including a 2006 photo by Jane Wiggins of Cedar Rapids, Iowa, that went viral online, said Gavin Pretor-Pinney, president of the society.

The roots of the International Cloud Atlas date to the 19th century: The first one contained 28 colored pictures in 1896. The most recent full edition was published in 1975, with a revision in 1987.

The new atlas, with updated photos and descriptions, should be out next year. It's published by the United Nations' World Meteorological Organization (WMO) in Geneva, which has the final say in cloud classification.

"I see the Cloud Atlas as the business card of the WMO," said Bertrand Calpini, president of the commission for instruments and methods of observations, which is overseeing the project.

There are 10 basic classifications of clouds:

• High clouds: Cirrus, Cirrocumulus and Cirrostratus

• Middle clouds: Altocumulus, Altostratus and Nimbostratus

• Low clouds: Stratocumulus, Stratus, Cumulus and Cumulonimbus

These 10 types are then subdivided into 14 species (secondary classifications), which describe their shape and internal structure, and 9 varieties (tertiary classifications), which describe the transparency and arrangement of clouds.

In addition to these first three levels, certain supplementary features and accessory clouds are also defined in a fourth level of description. It's at this level that asperatus will appear.

The revised atlas may also include the new cloud species Volutus — Latin for "rolled." Some new "special clouds" could also make an appearance, including the Homogenitus — from the Latin "homo" meaning man and "genitus" meaning generated or made — whose common names include contrails from aircraft.

A sighting of asperatus clouds this year in Georgia made the rounds on social media:

USA TODAY


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