The world's cloud authority, having not classified a new cloud in three decades, arose Thursday to name about a dozen new types, including a rolling, slalom-like form known to blanket the Iowa sky.
The asperitas cloud is among the stars of the World Meteorological Organization's scarcely published International Cloud Atlas. A new version of the atlas, last published in 1987, was unveiled on Thursday, World Meteorological Day.
Adding asperitas to the atlas' about 100 cloud combinations was the work of the world-wide Cloud Appreciation Society. Photos of asperitas clouds "captured the popular imagination around the world," noted the WMO. The society's website said they proposed the asperitas back in 2008 after receiving photographs from its members across the world. CAS first learned of asperitas clouds in 2006, when a reader sent in a stunning image of one from Cedar Rapids, Iowa.
"Asperitas was first identified with the help of citizen science, enabled by modern technology," said Cloud Appreciation Society Founder Gavin Pretor-Pinney. "When Cloud Appreciation Society members send us photographs of dramatic skies from around the world, it is possible to spot new patterns."
The book, which classifies and defines clouds, first published in 1896 and, according to WMO, "is the single most most authoritative and comprehensive reference for identifying clouds." The atlas' information is used by 191 countries.
Among the new clouds were five "supplementary features," which included asperitas and five "special clouds." Stand-outs included the volutus, which the organization describes as a "tube-shaped cloud mass" that streaks horizontally across the sky. There are also man-made contrails, vapor trails left by airplanes lasting at least 10 minutes.
The online version of the atlas is a step into the 21st Century for the WMO. The last edition, which was a companion version to the 1975 edition, had only been available in a printed form.
The atlas organizes clouds by genera, which is based on location and appearance, and are further split into species, which relates to shape and structure, and then "varieties," referring to a cloud's transparency and arrangement.
The WMO used the opportunity to express the importance of cloud research.
"If we want to forecast weather we have to understand clouds," said WMO Secretary-General Petteri Taalas. "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."
Contributing: Doyle Rice, USA TODAY