![](\"http:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2015\/01\/venus_express_snaps_swirling_vortex\/15199103-1-eng-GB\/Venus_Express_snaps_swirling_vortex_small.jpg\")
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\nThis ghostly puff of smoke is actually a mass of swirling gas and cloud at Venus\u2019 south pole, as seen by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA\u2019s Venus Express spacecraft.\n<\/p>\n
\nVenus has a very choppy and fast-moving atmosphere \u2013 although wind speeds are sluggish at the surface, they reach dizzying speeds of around 400 km\/h at the altitude of the cloud tops, some 70 km above the surface. At this altitude, Venus\u2019 atmosphere spins round some 60 times faster than the planet itself. This is very rapid; even Earth\u2019s fastest winds move at most about 30% of our planet\u2019s rotation speed. Quick-moving Venusian winds can complete a full lap of the planet in just four Earth days.\n<\/p>\n
\nPolar vortices form because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex much like that found above the plughole of a bath. In 1979, the Pioneer Venus orbiter spotted a huge hourglass-shaped depression in the clouds, some 2000 km across, at the centre of the north polar vortex. However, other than brief glimpses from the Pioneer Venus and Mariner 10 missions in the 1970s, Venus\u2019 south pole had not been seen in detail until ESA\u2019s Venus Express first entered orbit in April 2006.\n<\/p>\n
\nOne of Venus Express\u2019 first discoveries, made during its very first orbit, was confirming the existence of a huge atmospheric vortex circulation at the south pole with a shape matching the one glimpsed at the north pole.\n<\/p>\n
\nThis south polar vortex is a turbulent mix of warming and cooling gases, all surrounded by a \u2018collar\u2019 of cool air. Follow-up Venus Express observations in 2007, including this image, showed that the core of the vortex changes shape on a daily basis. Just four hours after this image the vortex looked very different<\/a> and a day later it had morphed into a squashed shape<\/a> unrecognisable from the eye-like structure here.\n<\/p>\n \nA video of the vortex, made from 10 images taken over a period of five hours, can be seen here<\/a>. The vortex rotates with a period of around 44 hours.\n<\/p>\n \nThe swirling region shown in this VIRTIS image is about 60 km above the planet\u2019s surface. Venus\u2019 south pole is located just up and to the left of the image centre, slightly above the wispy \u2018eye\u2019 itself.\n<\/p>\n \nThis image was obtained on 7 April 2007 at a wavelength of 5.02 micrometres. It shows thermal-infrared emission from the cloud tops; brighter regions like the \u2018eye\u2019 of the vortex are at lower altitude and therefore hotter.<\/p>\n","protected":false},"excerpt":{"rendered":" \t\t\t\t\t \nThis ghostly puff of smoke is actually a mass of swirling gas and cloud at Venus\u2019 south pole, as seen by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA\u2019s Venus Express spacecraft.\n<\/p>\n \nVenus has a very choppy and fast-moving atmosphere \u2013 although wind speeds are sluggish at the surface, they reach dizzying speeds of around 400 km\/h at the altitude of the cloud tops, some 70 km above the surface. At this altitude, Venus\u2019 atmosphere spins round some 60 times faster than the planet itself. This is very rapid; even Earth\u2019s fastest winds move at most about 30% of our planet\u2019s rotation speed. Quick-moving Venusian winds can complete a full lap of the planet in just four Earth days.\n<\/p>\n \nPolar vortices form because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex much like that found above the plughole of a bath. In 1979, the Pioneer Venus orbiter spotted a huge hourglass-shaped depression in the clouds, some 2000 km across, at the centre of the north polar vortex. However, other than brief glimpses from the Pioneer Venus and Mariner 10 missions in the 1970s, Venus\u2019 south pole had not been seen in detail until ESA\u2019s Venus Express first entered orbit in April 2006.\n<\/p>\n \nOne of Venus Express\u2019 first discoveries, made during its very first orbit, was confirming the existence of a huge atmospheric vortex circulation at the south pole with a shape matching the one glimpsed at the north pole.\n<\/p>\n \nThis south polar vortex is a turbulent mix of warming and cooling gases, all surrounded by a \u2018collar\u2019 of cool air. Follow-up Venus Express observations in 2007, including this image, showed that the core of the vortex changes shape on a daily basis. Just four hours after this image the vortex looked very different<\/a> and a day later it had morphed into a squashed shape<\/a> unrecognisable from the eye-like structure here.\n<\/p>\n<\/p>\n