Atmosphere 15.1

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Atmosphere 15.1

  1. 1. CH. 15-1 EARTH’S ATMOSPHERE
  2. 2. Importance  Atmosphere – a thin layer of air that forms a protective covering around Earth.  It keeps Earth’s temperature in a range that can support life.
  3. 3. Importance  It also protects life-forms from some of the Sun’s harmful rays.
  4. 4. Makeup of Atmos.  It is a mixture of solids, liquids, & gases that surround the planet.
  5. 5. Gases in the Atmos.  Nitrogen = 78%  Oxygen = 21%  CO2 = 0.03%, but could be increasing due to burning fossil fuels for energy.
  6. 6. Layers of the Atmos.  5 layers make up Earth’s atmosphere:  Troposphere & Stratosphere  Mesosphere, thermosphere, & exosphere
  7. 7. Lower Layers  Troposphere - the lowest layer of Earth’s atmosphere.  Extends up about 11 mi or 10 km  Contains clouds, rain, & snow.
  8. 8. Lower Layers  Stratosphere is directly above troposphere  Extends from 10 km – 50 km abut Earth’s surface  Contains a gas called ozone (O3)
  9. 9. Upper Layers  Mesosphere – extends from top of stratosphere to about 85 km above Earth  Shooting stars (meteors) occur here
  10. 10. Upper Layers  Thermosphere – the thickest layer of the atmosphere (between 85 km & 500 km) above Earth.  Very hot! Temps. can reach 2000 degrees!
  11. 11. Upper Layers  Ionosphere is a layer of electrically charged particles found within the thermosphere.  Absorbs AM radio waves during day, reflects them at night.
  12. 12. Upper Layers  Exosphere – last (highest) layer of the atmosphere  Extends more than 500 km above Earth (very cold)  Marks the transition from Earth’s atmosphere to outer space.
  13. 13. Atmospheric Pressure  Earth’s gravity pulls atmospheric gases toward its surface, & the weight of the gases presses down on the air below.  Air pressure decreases with height.
  14. 14. Ozone Layer  Lies within the stratosphere.  Blocks Sun’s harmful energy (UV radiation) which is very important to us.  UV = Ultraviolet
  15. 15. CFCs  CFCs - chlorofluorocarbons  They destroy ozone by the chlorine combining with one of the oxygen atoms in ozone.  Allows more UV light to reach the Earth.
  16. 16. CFCs  CFCs are found in Freon (used to cool refrigerators, air conditioners) & aerosol spray cans (hair spray & spray paints)  One atom of chlorine can destroy 100,000 ozone molecules!!

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