Explanation: What kind of cloud is this? A roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud. When this happens uniformly along an extended front, a roll cloud may form. Roll clouds may actually have air circulating along the long horizontal axis of the cloud. A roll cloud is not thought to be able to morph into a tornado. Unlike a similar shelf cloud, a roll cloud, a type of Arcus cloud, is completely detached from their parent cumulonimbus cloud. Pictured above, a roll cloud extends far into the distance in 2009 January above Las Olas Beach in Maldonado, Uruguay.

Note: An APOD editor will review astronomy images of 2009,
hosted by the Amateur Astronomers Association of New York on Friday, January 8 at the American Museum of Natural History, NYC.

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.

Publikacii s klyuchevymi slovami: Roll cloud - weather - oblaka - meteorologiya Publikacii so slovami: Roll cloud - weather - oblaka - meteorologiya
Sm. takzhe: Volnistye oblaka nad observatoriei Las-Kampanas Grozovoe oblako nad Tehasom Grozovoi vorotnik nad Viskonsinom Trubchatye oblaka nad Nebraskoi Perlamutrovye oblaka nad Laplandiei Raduzhnaya oblachnaya shapka nad Kitaem Uhodyashee grozovoe oblako na zakate Vse publikacii na tu zhe temu >>