Clouds in 2009, the First

Clouds

In 2009, the first new cloud formation since 1951 was proposed for addition to the International Cloud Atlas of the World Meteorological Organization ("Altocumulus Undulatus Asperatus"). Only eighty cloud formations have earned their distinctive marks in the International Cloud Atlas (Olson). Named after the Latin for "turbulent undulation," or rough waves, the altocumulus undulatus asperatus would therefore be the first new clouds to be named in over fifty years (Michaels; Olson). The last cloud officially registered by the World Meteorological Organization was cirrus intortus ( "Asperatus: gathering storm to force new cloud name").

After receiving a plethora of photographs, the Cloud Appreciation Society deemed the unique formation worthy of consideration as being distinct from other types of cloud (Michaels). The founder of the Cloud Appreciation Society, Gavin Pretor-Pinney, first referred to the special formation as "Jacques Cousteau" formations because "the cloud base resembled a choppy sea when viewed from below," (Royal Meteorological Society). Pretor-Pinney claims that undulatus asperatus "don't seem to fit very easily into the existing classifications," (cited on "Asperatus: gathering storm to force new cloud name"). The name "undulatus asperatus" was chosen particularly because asperatus was a term "used by Classical poets to describe the sea when it has been agitated by strong winds," (Royal Meteorological Society). Apparently Virgil used the term aparatus to "describe the surface of the sea whipped up by the north wind," ("Asperatus: gathering storm to force new cloud name"). The Latin term for wave is "unda," (the Cloud Appreciation Society).

Referred to as an "atmospheric anomaly," the undulatus asperatus are relatively rare. They occur in specific geographic regions and are especially prevalent among the Plains regions of the United States (Olson). Photographs of undulatus asperatus also hail from Scotland and other parts of Northern Europe as well as Tasmania down under. Photographs of the undulatus asperatus reveal distinct and smooth wave formations, although the undersides often appear "rough and choppy" like ocean water (Michaels). The clouds tend to appear during morning or midday hours following, rather than preceding, storm activity (Michaels). The aviation industry regards all undulatus clouds as a sign of light to moderate turbulence ("Clouds"). The exact conditions under which undulus apparatus are formed are still being researched by organizations like the Royal Meteorological Society in the United Kingdom.

Ten basic genera of clouds are officially recognized including the most well-known ones such as nimbus, stratus, cumulus, and cirrus. Each of these genres of cloud is further divided into cloud species "which describe shape and internal structure," as well as cloud variety, "which describes the transparency and arrangement of clouds," (Royal Meteorological Society).

The World Meteorological Organization (WMO) currently maintains the international standards for cloud classification. Cloud classification is based on "where in the atmosphere they form, the amount of moisture they hold, their shape and appearance," (Royal Meteorological Society). The WMO classifies clouds-based partly on where in the atmosphere they form, using the term "etage." The lower the etage, the lower in the atmosphere the clouds appear. Undulatus clouds form in the high etage: between 20,000 and 60,000 feet above ground ("Cloud Species"). The cloud genera in the high etage have the prefix "cirro." Undulatus is one of the sub-species belonging to the cirrocumulus genus. One blogger claims that the undulatus asperatus is formed by the "interaction of the dry, moving air with the bottom of the existing cloud," ("New Cloud- Altocumulus Undulatus Asperatus"). This interaction "results in the rough appearance on the underside of the cloud, which is the part that we see from the ground," ("New Cloud- Altocumulus Undulatus Asperatus").