11_global_warming

11_global_warming - 1 The Earth Pale Blue Dot Earth as seen...

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Unformatted text preview: 1 The Earth Pale Blue Dot Earth as seen from Voyager 1, when it was 6 billion km from home. General Features Mass: M Earth = 6 x 10 27 g Radius: R Earth = 6378 km Density: = 5.5 g/cm 3 Age: 4.6 billion years Earth's Internal Structure Crust: thin. Much Si and Al (lots of granite). Two-thirds covered by oceans. How do we know? Mostly from Earthquakes Mantle is mostly solid, mostly basalt (Fe, Mg, Si). Cracks in mantle allow molten material to rise => volcanoes. Core temperature is 6000 K. Metallic - mostly nickel and iron. Outer core molten, inner core solid. Atmosphere very thin Earth's Atmosphere 78% Nitrogen 21% Oxygen gas is ionized by solar radiation ozone is O 3 , which absorbs solar UV efficiently, thus heating stratosphere commercial jet altitudes room temperature Original gases disappeared. Atmosphere is mostly due to volcanoes and plants! Ionosphere Particles in the upper reaches of the atmosphere are ionized by the sun. Radio signals below ~20 MHz can bounce off the ionosphere allowing Communication over the horizon 2 The Temperature of the Earth Neglecting other effects, at equilibrium the Earth would reradiate all of the energy received from the Sun and have an average temperature of -23 o C. Why is the average temperature of Earth so much (about 40 o C) higher? Convection Earth's surface heated by Sun. What would happen if it couldn't get rid of the energy as fast as it gets in? Convection causes both small-scale turbulence and large scale circulation patterns. It also occurs within Earth, on other planets, and in stars. Convection also occurs when you heat up water, or soup. The Greenhouse Effect Main greenhouse gases are H 2 O and CO 2 . If no greenhouse effect, surface would be 40 o C cooler! Demo Clicker Question: A leading cause of Global Warming is: A: Increased soot (smog) in the atmosphere. B: Increased carbon dioxide in the atmosphere. C: The Earth is getting closer to the sun. D: The luminosity of the sun is steadily increasing. Clicker Question: The Greenhouse effect would not occur if: A: The Earth had no atmosphere. B: The amount of carbon dioxide doubled. C: We got rid of all the forests. D: The Earth didnt have an ocean. Burning carbon-containing fossil fuels produces carbon dioxide. (Combustion) C + O 2 CO 2 Global Warming Basics Pollution is the Primary Cause Global Warming: The Greatest Threat 2006 Deborah L. Wiliams 3 1.8 1.4 1.1 0.7 0.4-0.4-0.7-1.1 Global Temperature Change (deg F) Year 1000 1200 1400 1600 1800 2000 380 360 340 320 300 280 CO 2 Concentration (ppm) 1000 Years of CO 2 and Global Temperature Change Temperature CO 2 CO 2 : Most Significant Greenhouse Pollutant...
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11_global_warming - 1 The Earth Pale Blue Dot Earth as seen...

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