Lec22-Apr9

Lec22-Apr9 - 4/9/10 Discussion Ques8on Astro 109...

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Unformatted text preview: 4/9/10 Discussion Ques8on Astro 109 Lecture 22: Atmospheres – Forma8on and Evolu8on, Mo8on April 9 The evolu8on of Earth’s atmosphere was greatly affected by the forma8on of oceans. Which of the following was not an important consequence of ocean forma8on? A.  B.  C.  D.  E.  Nitrogen was released in large quan88es. Most CO2 was removed from the atmosphere. Most water was removed from the atmosphere. The greenhouse effect was reined in. Aqua8c plants produced free oxygen. Apr. 9 Key Concepts •  Terrestrial planet atmospheres were similar to start, but grew apart •  Greenhouse effect and atmospheric evolu8on •  Convec8on and coriolis effect determine how air moves Apr. 9 Apr. 9 Earth Venus true acid rain (sulfuric acid) – but it evaporates before reaching the surface ozone absorbs UV from Sun “virga” on Earth Apr. 9 Apr. 9 1 4/9/10 Discussion Ques8on Mars The pressure of Mars’s atmosphere varies by as much as 25% during the course of a Mar8an year. Why? no liquid – only ice (water and CO2) Apr. 9 A.  B.  C.  D.  E.  Mars’s distance from the Sun varies by 25%. Mars’s albedo varies by 25%. Solar 8des induce more volcanic ac8vity at perihelion. Some of the gas freezes out of the atmosphere in winter. Microorganisms in Mar8an soil are more ac8ve during the summer. Apr. 9 Mamers Vallis Mars: Wet past? Ares Vallis Ganges Chasma Apr. 9 Apr. 9 Hephaestus Fossae Mars Express, ESA / DLR / FU Berlin Mars Odyssey, NASA / JPL / Arizona State University Discussion Ques8on Where do atmospheres come from? impacts by comets Apr. 9 outgassing from volcanoes Most of the water vapor outgassed from Earth’s interior A.  B.  C.  D.  E.  was destroyed by solar radia8on was incorporated into carbonate rocks (such as limestone) has escaped into space is found in today’s atmosphere is found in today’s oceans Apr. 9 2 4/9/10 Discussion Ques8on Most of the CO2 outgassed from Earth’s interior A.  B.  C.  D.  E.  Mars was destroyed by solar radia8on was incorporated into carbonate rocks (such as limestone) has escaped into space is found in today’s atmosphere is found in today’s oceans Apr. 9 Venus Apr. 9 Discussion Ques8on Most of the CO2 outgassed from Venus’s interior A.  B.  C.  D.  E.  was destroyed by solar radia8on was incorporated into carbonate rocks (such as limestone) has escaped into space is found in today’s atmosphere is found in today’s oceans Atmospheric evolu8on •  Venus, Earth, and Mars probably began with similar atmospheres. What happened? •  CO2 could be trapped in water and rocks (carbonates) – moderates greenhouse effect •  (On Earth, most of the CO2 is in the crust) •  CO2 could be recycled by volcanoes Apr. 9 Apr. 9 Modern carbon cycle Atmospheric evolu8on •  Earth: most CO2 trapped in oceans and carbonate rocks; some CO2 released by volcanoes  ­ ­> moderate greenhouse effect •  Venus: began similar to Earth, but rising temperatures  ­ ­> water evaporated  ­ ­> more warming  ­ ­> CO2 in rocks “baked out” runaway greenhouse effect •  Mars: smaller/cooler planet  ­ ­> volcanoes stopped sooner  ­ ­> CO2 permanently trapped  ­ ­> more cooling  ­ ­> more condensa8on (rain/ice)  ­ ­> more CO2 trapped  ­ ­> thin CO2 atmosphere Apr. 9 runaway icehouse effect Apr. 9 http://globecarboncycle.unh.edu/CarbonCycleActivities.shtml" 3 4/9/10 Discussion Ques8on Life! Most of the oxygen in Earth’s atmosphere today came from A.  B.  C.  D.  E.  •  photosynthesis releases oxygen the breakup of the ozone layer photosynthesis by plants spliing of CO2 molecules by solar radia8on outgassing from volcanoes mel8ng glaciers Apr. 9 •  oxygen is very reac8ve, but lots of life  ­ ­> lots of O2 •  21% O2 represents balance between photosynthesis and respira8on Apr. 9 Review: Earth Apr. 9 Review: Venus Apr. 9 Review: Mars Atmospheric mo8ons Apr. 9 Apr. 9 4 4/9/10 Convec8on Apr. 9 Venus: slow rota8on Earth: fast rota8on Apr. 9 Coriolis effect Apr. 9 Apr. 9 Hurricanes Wikipedia Apr. 9 Apr. 9 Wikipedia 5 4/9/10 Hurricanes Northern hemisphere Southern hemisphere Apr. 9 Apr. 9 Apr. 9 Apr. 9 Apr. 9 Apr. 9 6 4/9/10 Discussion Ques8on The evolu8on of Earth’s atmosphere was greatly affected by the forma8on of oceans. Which of the following was not an important consequence of ocean forma8on? A.  B.  C.  D.  E.  Apr. 9 Nitrogen was released in large quan88es. Most CO2 was removed from the atmosphere. Most water was removed from the atmosphere. The greenhouse effect was reined in. Aqua8c plants produced free oxygen. Apr. 9 HW ques8ons Chapter 11 29. Why are the pamerns of convec8on in the Venusian atmosphere so different from those in our atmosphere? 32. Why is it reasonable to assume that the primordial atmospheres of the Earth, Venus, and Mars were roughly the same? 33.  Carbon dioxide accounts for 95% of the present ­day atmospheres of both Mars and Venus. Why, then, is there a strong greenhouse effect on Venus but only a weak greenhouse effect on Mars? 34. (a) What is a runaway greenhouse effect? (b) What is a runaway icehouse effect? Apr. 9 7 ...
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This note was uploaded on 09/15/2011 for the course PHYS 109 taught by Professor Pryor during the Spring '09 term at Rutgers.

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