<P> Mikhail Lomonosov was the first person to hypothesize the existence of an atmosphere on Venus based on his observation of the transit of Venus of 1761 in a small observatory near his house in Saint Petersburg, Russia . </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> <P> Unlike Earth, Venus lacks a magnetic field . Its ionosphere separates the atmosphere from outer space and the solar wind . This ionised layer excludes the solar magnetic field, giving Venus a distinct magnetic environment . This is considered Venus's induced magnetosphere . Lighter gases, including water vapour, are continuously blown away by the solar wind through the induced magnetotail . It is speculated that the atmosphere of Venus up to around 4 billion years ago was more like that of the Earth with liquid water on the surface . A runaway greenhouse effect may have been caused by the evaporation of the surface water and subsequent rise of the levels of other greenhouse gases . </P> <P> Despite the harsh conditions on the surface, the atmospheric pressure and temperature at about 50 km to 65 km above the surface of the planet is nearly the same as that of the Earth, making its upper atmosphere the most Earth - like area in the Solar System, even more so than the surface of Mars . Due to the similarity in pressure and temperature and the fact that breathable air (21% oxygen, 78% nitrogen) is a lifting gas on Venus in the same way that helium is a lifting gas on Earth, the upper atmosphere has been proposed as a location for both exploration and colonization . </P>

Venus's atmosphere has much more carbon dioxide than earth's because