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    Venus, atmosphere

    Artist's impression of the surface of Venus
    Artist's impression of the surface of Venus
    Venus has a dense atmosphere, composed chiefly of carbon dioxide, which generates a surface pressure 90 times greater than that on Earth. This massive blanket of carbon dioxide is also responsible for a runaway greenhouse effect that heats the planet's surface to an average temperature of 467°C (872°F) – hot enough to melt lead.

    Venus' atmosphere consists almost entirely (97%) of carbon dioxide, with clouds containing droplets of sulfuric acid along with compounds of chlorine and fluorine. These precipitate an acid rain called virga, which evaporates before it has the chance to reach the surface. In the upper part of the atmosphere, clouds swirl by at a rate of 300 km/h, driven by fierce winds.


    Atmospheric composition at surface level Major components (by volume)
    96.5% carbon dioxide (CO2)
    3.5% nitrogen (N2)

    Minor components (parts per million)
    150 sulfur dioxide (SO2)
    70 argon (Ar)
    20 water vapor (H2O)
    17 carbon monoxide (CO)
    12 helium (He)
    7 neon (Ne)
    Surface pressure 92 bars
    Surface density ~65 kg/m3
    Surface wind speeds 0.3-1.0 m/s


    Venus atmosphere profile
    © 2005 Pearson Prentice Hall, Inc


    History of observations

    That Venus was permanently enveloped in what appeared to be thick, white clouds soon became clear following the development of the telescope. By analogy with the Earth, it was generally assumed that these clouds were made of water vapor, a conclusion supported by early spectroscopic studies by Secchi. The main composition of the atmosphere remained a matter for conjecture until spectroscopic observations by Walter Adams and Theodore Dunham, in 1932, established that it was carbon dioxide. Speculation about the make-up of the clouds continued. In 1937, R. Wildt suggested methanal (formaldehyde), while in 1954, Fred Whipple and Donald Menzel proposed ice crystals. Today, they are known to consist primarily of sulfuric acid.


    Related entries

        Venus, life
        ashen light
        Mars, atmosphere


    Related category

       • PLANETS AND MOONS



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