Lecture18 - Lecture#18 Venus atmosphere and climate...

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1 Astro 102/104 1 Lecture #18: Venus atmosphere and climate • Properties of the atmosphere. • Greenhouse Effect. • Climate Implications. • Readings: –Chapters 9.5, 9.6, 10.5, 10.6. Astro 102/104 2 The Main Point Venus has a thick carbon dioxide atmosphere that creates an extreme greenhouse effect. Earth and Venus have had divergent evolutionary histories despite similar sizes and compositions. Astro 102/104 3 Atmospheric Composition Composition determined by spectroscopy from ground based telescopes and direct sampling from landers and balloons (!) The Atmospheres of Venus and Earth Gas Venus Earth Carbon Dioxide (CO 2 ) 96.0% 0.03% Nitrogen (N 2 ) 3.5 78.1 Argon (Ar) 0.006 0.93 Oxygen (O 2 ) 0.003 21.0 Neon (Ne) 0.001 0.002 Astro 102/104 4 Atmospheric Structure • Atmosphere divided into layers like Earth's. • Enormous clear and hot troposphere. • Clouds of sulfuric acid! (not water!) • CO 2 , Sulfur may be volcanic in origin, but we have not yet detected any direct evidence for active volcanism now. • Surface temp ~ 480°C. • Surface pressure ~ 90 bars (same pressure as ~1 km under water). (artistic license: no proof)
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