<Tr> <Th> Hydrogen chloride </Th> <Td> 0.1--0.6 ppm </Td> </Tr> <Tr> <Th> Hydrogen fluoride </Th> <Td> 0.001--0.005 ppm </Td> </Tr> <P> The atmosphere of Venus is the layer of gases surrounding Venus . It is composed primarily of carbon dioxide and is much denser and hotter than that of Earth . The temperature at the surface is 740 K (467 ° C, 872 ° F), and the pressure is 93 bar (9.3 MPa), roughly the pressure found 900 m (3,000 ft) underwater on Earth . The Venusian atmosphere supports opaque clouds made of sulfuric acid, making optical Earth - based and orbital observation of the surface impossible . Information about the topography has been obtained exclusively by radar imaging . Aside from carbon dioxide, the other main component is nitrogen . Other chemical compounds are present only in trace amounts . </P> <P> Aside from the very surface layers, the atmosphere is in a state of vigorous circulation . The upper layer of troposphere exhibits a phenomenon of super-rotation, in which the atmosphere circles the planet in just four Earth days, much faster than the planet's sidereal day of 243 days . The winds supporting super-rotation blow at a speed of 100 m / s (~ 360 km / h or 220 mph) or more . Winds move at up to 60 times the speed of the planet's rotation, while Earth's fastest winds are only 10% to 20% rotation speed . On the other hand, the wind speed becomes increasingly slower as the elevation from the surface decreases, with the breeze barely reaching the speed of 10 km / h (2.8 m / s) on the surface . Near the poles are anticyclonic structures called polar vortices . Each vortex is double - eyed and shows a characteristic S - shaped pattern of clouds . Above there is an intermediate layer of mesosphere which separates the troposphere from the thermosphere . The thermosphere is also characterized by strong circulation, but very different in its nature - the gases heated and partially ionized by sunlight in the sunlit hemisphere migrate to the dark hemisphere where they recombine and downwell . </P>

The atmospheric pressure on the surface of venus is