:Asperitas (cloud)
{{Short description|Supplementary cloud}}
{{For|the genus of snails|Asperitas}}
{{Infobox Cloud
| name = Asperitas
| image location = File:Asperitas clouds over Dayton, Ohio on October 21, 2023.jpg
| image name = Asperitas over Dayton, Ohio in 2023
| abbreviation =
| symbol =
| genus= Altocumulus or Stratocumulus depending on height, as Asperitas is thought to be a cumuliform structure {{cite web|url=http://cloudappreciationsociety.org/june-09/ |title=June 2009 |publisher=The Cloud Appreciation Society |access-date=2012-12-20}}
| species= Stratiformis
| variety= Opacus
| supplementary feature= asperitus
| altitude_m = Below 2,000 (or higher with altocumulus)
| altitude_ft = Below 6,000 -or higher with altocumulus-
| level = low or middle
| appearance = Wavy undersurface
| precipitation = No, but may form near storm clouds.
| thickness =
| Ice content =
}}
Asperitas (formerly known as Undulatus asperatus) is a cloud formation first popularized and proposed as a type of cloud in 2009 by Gavin Pretor-Pinney of the Cloud Appreciation Society. Added to the International Cloud Atlas as a supplementary feature in March 2017, it is the first cloud formation added since cirrus intortus in 1951.{{Cite news |date=2009-06-03 |title=PICTURES: New Cloud Type Discovered? |page=National Geographic |work=National Geographic |publisher=National Geographic News |url=http://news.nationalgeographic.com/news/2009/06/photogalleries/new-cloud-pictures/ |access-date=2009-06-03 |archive-url=https://web.archive.org/web/20090608171213/http://news.nationalgeographic.com/news/2009/06/photogalleries/new-cloud-pictures/ |archive-date=8 June 2009 |url-status=dead}} The name translates approximately as "roughness".
The clouds are closely related to undulatus clouds. Although they appear dark and storm-like, they almost always dissipate without a storm forming. The ominous-looking clouds have been widespread in the Plains states of the United States, often during the morning or midday hours following convective thunderstorm activity.{{cite web|url=http://www.meteorologynews.com/2009/06/06/new-cloud-type-discovered-undulus-asperatus |title=New Cloud Type Discovered: 'Undulus Asperatus' |publisher=Meteorology News |date=2006-04-28 |access-date=2012-12-20}}
Definition
According to International Cloud Atlas, Asperitas are defined as
Well-defined, wave-like structures in the underside of the cloud; more chaotic and with less horizontal organization than the variety undulatus. Asperitas is 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 illumination levels and cloud thickness can lead to dramatic visual effects.Occurs mostly with Stratocumulus and Altocumulus.{{cite web |title=Asperitas |url=https://cloudatlas.wmo.int/en/clouds-supplementary-features-asperitas.html |website=International Cloud Atlas |access-date=9 April 2022 |language=EN}}
History
On June 20, 2006, Jane Wiggins took a picture of asperitas clouds from the window of a downtown office building in Cedar Rapids, Iowa, United States.{{cite news|title=Iowa Woman's Photo Sparks Push for New Cloud Type|author=MICHAEL J. CRUMB|url=http://www.physorg.com/news163990239.html|agency=Associated Press|date=2009-06-11 |access-date=25 April 2023}} Soon after taking it, Wiggins sent her Cedar Rapids image to the Cloud Appreciation Society, which displayed it on its image gallery.{{cite web|url=http://www.cloudappreciationsociety.org/gallery/index.php?showimage=1692 |title=Cloud Photos |publisher=The Cloud Appreciation Society |access-date=2012-12-20}} Since 2006, many similar cloud formations have been contributed to the gallery, and in 2009 Gavin Pretor-Pinney, founder of The Cloud Appreciation Society, began working with the Royal Meteorological Society to promote the cloud type as an entirely new type.{{cite news |url=https://www.theguardian.com/environment/gallery/2009/jun/01/2?picture=348217732|publisher=The Guardian|title=Asperatus: gathering storm to force new cloud name | location=London | date=2009-06-02 | access-date=2010-03-28}} Wiggins' photograph was posted on the National Geographic website on June 4, 2009.
In 2009, it was reported that Margaret LeMone, a cloud expert with the American National Center for Atmospheric Research, had taken photos of asperitas clouds for 30 years and considered it a new cloud type.
On July 23, 2013, Janet Salsman photographed them along the South Shore of Nova Scotia, Canada. On October 28, 2013, an asperitas cloud layer formed over Tuscaloosa, Alabama, United States.{{cite web |author=James Spann |url=https://plus.google.com/108868884822043573742/posts/gBbvhByxGW8 |archive-url=https://archive.today/20131030093750/https://plus.google.com/108868884822043573742/posts/gBbvhByxGW8 |url-status=dead |archive-date=October 30, 2013 |title=document formerly at plus.google.com}}
On July 7, 2014, asperitas clouds in Lincoln, Nebraska, United States, were filmed by Alex Schueth.{{cite web |author=Alex Schueth |url=https://www.youtube.com/watch?v=Jz7BgxrVmiQ |title=Undulatus Asperatus |access-date=25 April 2023}} One of the most dramatic formations was captured by Witta Priester in New Zealand in 2005. NASA posted the photo as the Astronomy Picture of the Day, which shows great detail, partly because sunlight illuminates the undulating clouds from the side.{{Cite web |url=https://apod.nasa.gov/apod/ap130227.html |title=APOD: 2013 February 27 - Asperatus Clouds Over New Zealand |website=apod.nasa.gov |access-date=25 April 2023}}
The 2017 edition of the World Meteorological Organisation (WMO)'s International Cloud Atlas included asperitas as a supplementary feature. Pretor-Pinney gave an invited presentation at the WMO in Geneva for the launch of the revised Cloud Atlas on World Meteorological Day 2017. He has worked with scientists at the [http://www.reading.ac.uk/met/ Department of Meteorology], University of Reading on possible mechanisms for the formation of asperitas, co-authoring a paper published in the Royal Meteorological Society's journal Weather.{{Cite journal|last=Harrison|first=R. Giles|last2=Pretor‐Pinney|first2=Gavin|last3=Marlton|first3=Graeme J.|last4=Anderson|first4=Graeme D.|last5=Kirshbaum|first5=Daniel J.|last6=Hogan|first6=Robin J.|date=2017|title=Asperitas – a newly identified cloud supplementary feature|journal=Weather|language=en|volume=72|issue=5|pages=132–141|doi=10.1002/wea.2996|issn=1477-8696|url=http://centaur.reading.ac.uk/69830/1/AsperitasPaper_revised2.pdf}}
See also
References
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