Chapter 7 Notes - ISP 205 - Chapter 7 Page 1 7.1 Earth as a...

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ISP 205 - Chapter 7 Page 1 7.1 Earth as a Planet I. Why earth is Geologically Active A. The Magnetic Field 1. Responsible for interior heat 2. Generated by a process similar to that of an electromagnet, in which the magnetic field arises as a battery forces charged particles to move along a coiled wire 3. Earth’s magnetic field is generated by the motions of molten metal in its liquid outer core 4. Internal heat causes the liquid metal to rise and fall – convection a. Earth’s rotation and distorts convection pattern b. Result – electron will move within the outer core in the same way as in an electromagnet c. Generates Earth’s magnetic field 5. Protection a. Surface from energetic particles from the Sun i. could strip away atmospheric gas ii. Cause genetic damage to living organisms b. Creates Magnetosphere – protective bubble that surrounds our planet i. Deflects most charged particles ii. Few that make it through are channeled toward the poles iii. They then collide with atoms and molecules in atmosphere and produce the lights of an aurora – strongest when solar winds buffet the magnetosphere, energizing the charged particles 6. Earth has the strongest magnet field out of the terrestrial planet II. How does Earth’s atmosphere affect the planet? A. 77% nitrogen, 21% oxygen, and small amounts of other gases B. General Purposes 1. Air we breathe 2. Pressure allowing liquid water to flow 3. Without, Earth’s surface would be lifeless by solar radiation 4. Water would be frozen C. Thin atmosphere – 2/3 of air lie within 10 km of the surface D. Surface protection 1. Sun emits dangerous UV and xray radiation 2. Xray a. Ionize – xray protons carry enough energy to knock electrons free from atoms and molecules b. Damages living tissue c. But are absorbed easily by atmosphere (higher up) 3. UV a. Not so easily absorbed, gases are transparent allowing it to pass through b. Protection from Ozone (O3) i. Middle layer of atmosphere ii. Life on land would be impossible without it 4. Visible Light a. Most of radiation emitted by Sun b. Reaches Surface i. Allows us to see
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ISP 205 - Chapter 7 Page 2 ii. Energy for photosynthesis c. Primary source of heat for Earth’s surface 5. Scattering of Visible Light a. Why sky is brighter rather than dark b. Without, the Sun would just be a bright circle set against black, starry background c. Blue Sky i. Visible light consists of all the colors of the rainbow ii. Gas molecules scatter blue light (higher energy) more effectively d. Sunrise and Sunset i. Sunlight must pass through a great amount of atmosphere ii. Most blue light is scattered away, leaving only red light to color the sky E. Greenhouse Effect 1. Visible light itself would only give Earth a temperature of -16 C (+3F); actual average = 15C (59F) 2. Greenhouse effect – atmosphere traps additional heat, allowing water to stay liquid 3. Planets emit energy primarily in the form of infrared and atmosphere traps it, slowing its return to space
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This note was uploaded on 03/19/2008 for the course ISP 205 taught by Professor Donahue during the Spring '08 term at Michigan State University.

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Chapter 7 Notes - ISP 205 - Chapter 7 Page 1 7.1 Earth as a...

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