Imagens do Mundo - Sitios lindos de Portugal - Sintra

Uma nuvem, um palacio, jardins, museus... até chegar ao castelo dos Mouros... e ao Palacio da minha Pena...Sintra...

SEAN PAVONE/ISTOCK

Astronomy picture of the day - 2016 June 12 - A Roll Cloud Over Uruguay

A Roll Cloud Over Uruguay 
Credit & Licence: Daniela Mirner Eberl

Explanation: What kind of cloud is this? A type of arcus cloud called 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 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.