earth - Announcements Pale Blue Dot Homework #3 is due on...

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1 Announcements Homework #3 is due on Thursday 9/22 Pale Blue Dot Earth as seen from Voyager 1, when it was 6 billion km from home. The Earth General Features Mass: M Earth = 6 x 10 27 g Radius: R Earth = 6378 km Density: ρ = 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? Earthquakes. See later 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 temperature on a cool day Original gases disappeared. Atmosphere is mostly due to volcanoes and plants!
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2 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” (or mountains) 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 boil water, or soup. Think of Earth's surface as a boiling pot! The Greenhouse Effect Main greenhouse gases are H 2 O and CO 2 . If no greenhouse effect, surface would be 40 o C cooler! Clicker Question: The dinosaurs were most likely wiped out by: A: disease B: hunting to extinction by cavemen C: a giant meteor impact D: the close passage of another star 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 didn’t have an ocean.
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3 Burning carbon-containing fossil fuels produces carbon dioxide. (Combustion) C + O 2 CO 2 Global Warming Basics Burning Fossil Fuels is the Primary Cause Global Warming: The Greatest Threat © 2006 Deborah L. Wiliams Global Warming Basics Humans have increased carbon dioxide (CO 2 ) in the atmosphere by more than 35% since the Industrial Revolution .
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earth - Announcements Pale Blue Dot Homework #3 is due on...

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