Nimbostratus cloud 166737 220539092 2008-06-20T10:30:13Z 196.25.43.208 {{Expand|date=March 2007}} {{Infobox Cloud | name = Nimbostratus cloud | image location = Nov20-05-Nimbostratus.jpg | image name =Heavy nimbostratus cover with some cumuliform fractus. | abbreviation = Ns | distributed = worldwide | symbol = CM_2.png | genus= Nimbo- (''rain'')<br /> -stratus (''layered'') | species= cloud | variety= cloudy | altitude_m = below 2,400 | altitude_ft = below 8,000 | level = low | appearance = Dark, Widespread, formless layer | precipitation = Yes, but may be [[virga]] }} Nimbo is from the Latin word "nimbus" meaning rain. A '''Nimbostratus''' is a [[cloud]] of the class characterized by a formless layer that is almost uniformly dark gray; it is a rain cloud of the layer type, of medium altitude, usually developing above 6500 ft (2000 m) as defined by the [[WMO]]. It may drop below 2000m and is classified in some nations as low level cloud. Nimbostratus block a great amount of [[sunlight]] as a result of its characteristic dense structure. Nimbostratus usually has a thickness of 6,500-10,000 ft (2,000-3,000 meters), but can vary from 15,000 ft (4,500 m) to 3,500 ft (1,000 m) in thickness. In rare cases, nimbostratus can be very thin and accompanied by a separate layer of [[Altostratus cloud|altostratus]] divided by a cloudless layer. The base of a nimbostratus [[Cloud_base|base]] cloud is dimmed by precipitation and is usually not clearly visible. In most cases, nimbostratus is accompanied by [[Fractus_cloud|pannus]] clouds, which develop under layer of nimbostratus. If [[Fractus_cloud|pannus]] layer is completely opaque, presence of precipitation indicates presence of nimbostratus. The [[Fractus cloud|pannus]] movement is slow and uniform under nimbostratus. [[Image:Nimbostratus.jpg|thumb|300px|left|Nimbostratus has very few visual features.]] Nimbostratus, [[Stratus cloud|stratus]], [[Altostratus cloud|altostratus]] and [[stratocumulus]] clouds all have a smooth gray appearance. Usually, nimbostratus is a sign of steady moderate to heavy precipitation. However, precipitation does not occur at ground level in case of [[virga]] and accompanies other cloud types. There are a number of features allowing the observer to distinguish nimbostratus from other clouds: * [[Stratus cloud|Stratus clouds]] bring much lighter precipitation (drizzle) than nimbostratus; * [[Altostratus cloud|Altostratus clouds]] are lighter in color and less opaque than nimbostratus, so sunlight can be seen through them; * [[Cirrostratus cloud|Cirrostratus clouds]] never bring precipitation and have a thin, whitish, veil-like structure, characteristic for cirrus; * [[Stratocumulus]] bring only light precipitation and have clearly visible [[Cloud_base|base]] with easely distinguished separate cloud elements. Moreover, large and low [[cumulonimbus cloud]] covering most of sky can be mistaken for nimbostratus. In this case, nimbostratus can be distinguished by lighter, constant precipitation. Other typical precipitation-bearing clouds are [[cumulonimbus cloud|cumulonimbus]]. ==External links== {{commonscat|Nimbostratus clouds}} *[http://www.clouds-online.com Clouds-Online.com Cloud Atlas with many photos and description of the different cloud genus] * [http://www.nsdl.arm.gov/Library/glossary.shtml#Nimbostratus National Science Digital Library - Nimbostratus] * [http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/atmospheric_moisture/clouds_3.html Nimbostratus and Other Low Clouds] {{Cloud types}} [[Category:Cloud types]] [[ca:Nimbostratus]] [[cs:Nimbostratus]] [[de:Nimbostratus]] [[el:Μελανοστρώματα]] [[es:Nimbostratus]] [[fr:Nimbostratus]] [[gl:Nimbostratus]] [[ko:난층운]] [[it:Nembostrato]] [[he:נימבוסטרטוס]] [[nl:Nimbostratus]] [[ja:乱層雲]] [[no:Nimbostratus]] [[nn:Nimbostratus]] [[pl:Nimbostratus]] [[pt:Nimbostratus]] [[sk:Nimbostratus]] [[sl:Nimbostratus]] [[fi:Laaja sadepilvi]] [[sv:Nimbostratus]] [[uk:Шарувато-дощові хмари]]