1Astro 102/1041Lecture #18: Venus atmosphere and climate• Properties of the atmosphere.• Greenhouse Effect.• Climate Implications.• Readings:–Chapters 9.5, 9.6, 10.5, 10.6.Astro 102/1042The Main PointVenus 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 102/1043Atmospheric Composition•Composition determined by spectroscopy from ground based telescopes and direct sampling from landers and balloons (!)The Atmospheres of Venus and EarthGasVenusEarthCarbon Dioxide (CO2)96.0%0.03%Nitrogen (N2)3.578.1Argon (Ar)0.0060.93Oxygen (O2)0.00321.0Neon (Ne)0.0010.002Astro 102/1044Atmospheric Structure• Atmosphere divided into layers like Earth's.• Enormous clear and hot troposphere.• Clouds of sulfuric acid!(not water!)• CO2, 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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