Um redemoinho de vento numa tarde em Marte eleva uma coluna de poeira giratória com mais de 800 metros de altura, nesta imagem da câmera High Resolution Imaging Science Experiment (HiRISE) a bordo do Mars Reconnaissance Orbiter.
O HiRISE captou a imagem em 16 de fevereiro de 2012, enquanto o orbital passava sobre a região da Amazonis Planitia, no norte de Marte.Na área observada, marcas de redemoinhos anteriores, ou demônios de poeira, são visíveis como trilhas na superfície poeirenta.
O demônio de poeira ativo mostra um delicado arco produzido por uma brisa do oeste parcialmente da sua altura. A coluna de poeira tem cerca de 30 metros de diâmetro.
A imagem foi obtida durante a época do ano Marciano quando o planeta está mais afastado do Sol. Assim como na Terra, os ventos em Marte são causados pelo aquecimento solar. A exposição aos raios do Sol declina durante esta estação, no entanto, mesmo agora, os demônios de poeira atuem implacavelmente para limpar a superfície da poeira recém-depositada, um pouco de cada vez.
Os demônios de poeira ocorrem na Terra, assim como em Marte. Eles são clunas giratórias de ar, tornadas visíveis pela poeira que sugam do solo. Diferentemente dos tornadoa, um demônio de poeira forma-se tipicamente em dias claros, quando o solo está aquecido pelo Sol, esquentando o ar acima do chão. Quando o ar aquecido próximo à superfície sobe rapidamente através de um pequeno bolsão de ar mais frio acima dele, o ar pode começar a girar, se as condições forem adequadas.
An afternoon whirlwind on Mars lofts a twisting column of dust more
than half a mile (800 meters) high in an image from the High Resolution
Imaging Science Experiment (HiRISE) camera on NASA's Mars
Reconnaissance Orbiter.
HiRISE captured the image on Feb. 16, 2012, while the orbiter passed over the Amazonis Planitia region of northern Mars. In the area observed, paths of many previous whirlwinds, or dust devils, are visible as streaks on the dusty surface.
The active dust devil displays a delicate arc produced by a westerly breeze partway up its height. The dust plume is about 30 yards or meters in diameter.
The image was taken during the time of Martian year when that planet is farthest from the sun. Just as on Earth, winds on Mars are powered by solar heating. Exposure to the sun's rays declines during this season, yet even now, dust devils act relentlessly to clean the surface of freshly deposited dust, a little at a time.
Dust devils occur on Earth as well as on Mars. They are spinning columns of air, made visible by the dust they pull off the ground. Unlike a tornado, a dust devil typically forms on a clear day when the ground is heated by the sun, warming the air just above the ground. As heated air near the surface rises quickly through a small pocket of cooler air above it, the air may begin to rotate, if conditions are just right.
HiRISE captured the image on Feb. 16, 2012, while the orbiter passed over the Amazonis Planitia region of northern Mars. In the area observed, paths of many previous whirlwinds, or dust devils, are visible as streaks on the dusty surface.
The active dust devil displays a delicate arc produced by a westerly breeze partway up its height. The dust plume is about 30 yards or meters in diameter.
The image was taken during the time of Martian year when that planet is farthest from the sun. Just as on Earth, winds on Mars are powered by solar heating. Exposure to the sun's rays declines during this season, yet even now, dust devils act relentlessly to clean the surface of freshly deposited dust, a little at a time.
Dust devils occur on Earth as well as on Mars. They are spinning columns of air, made visible by the dust they pull off the ground. Unlike a tornado, a dust devil typically forms on a clear day when the ground is heated by the sun, warming the air just above the ground. As heated air near the surface rises quickly through a small pocket of cooler air above it, the air may begin to rotate, if conditions are just right.
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