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OZONE DEPLETION

OZONE DEPLETION. Videos. Weather Ch. NASA 1. 2009 “hole”. Blocks UV radiation. Stratosphere: Good. Troposphere: Bad. Damages human health and welfare. The ozone layer is in the Stratosphere. The ozone layer blocks 95-99% of the sun’s Ultraviolet Radiation.

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OZONE DEPLETION

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  1. OZONE DEPLETION

  2. Videos Weather Ch. NASA 1 2009 “hole”

  3. Blocks UV radiation Stratosphere: Good Troposphere: Bad Damages human health and welfare

  4. The ozone layer is in the Stratosphere

  5. The ozone layer blocks 95-99% of the sun’s Ultraviolet Radiation

  6. UV Radiation has negative effects • O3 Depletion causes higher UV Radiation which causes: • Sunburn • Skin Cancer • Eye Cataracts • Weakened Immune System • Reduced crop yield • Damages to marine ecosystem, etc. • More photochemical smog to form (including O3) Link to EPA Site on Effects

  7. Ozone Formation • Oxygen in Troposphere makes it into Stratosphere. • UV radiation in stratosphere converts O2 to O3.

  8. Ozone Formation UV Stratosphere Troposphere O2 O2 O2 Oxygen in troposphere goes into stratosphere

  9. Ozone Formation UV O2 O2 O O Stratosphere Troposphere UV breaks O2 into two atomic oxygens (O)

  10. Ozone Formation UV O3 O3 Stratosphere Troposphere O2 O2 The atomic O binds with O2 to make O3 (ozone)

  11. Ozone Destruction • Cause: CFCs and other Chlorine- and Bromine-containing molecules • Used for aerosol spray cans, Styrofoam inflation, air conditioners and refrigerators (Freon), pesticides, and other industrial processes. Link to EPA site of ozone-depleting substances

  12. Ozone Destruction UV CFCs travel into stratosphere O3 Stratosphere Troposphere O2 O2 CFC

  13. Ozone Destruction UV UV breaks off a Chlorine atom Cl O3 Stratosphere Troposphere O2 O2

  14. Ozone Destruction UV The Chlorine atom takes an O atom from ozone, converting ozone to chlorine monoxide and oxygen ClO O2 Stratosphere Troposphere O2 O2

  15. Ozone Destruction Cunningham/Cunningham 2002 text

  16. Where is Ozone Depletion? • Everywhere: Global thinning • E.g.: US sees 5-10% drop • Note: this is enough to significantly increase skin cancer, etc. • Highest over Antarctic (also Arctic) • Polar vortex, cold temps, long winter produce polar stratospheric clouds upon which reactions occur. • Where the so-called ozone hole occurs (where ozone less than 220 dobson units – a 70% reduction; normal is 250-475+).

  17. Increasing Ozone Depletion “a column ozone level of less than 220 Dobson Units is a result of the ozone loss from chlorine and bromine compounds” http://ozonewatch.gsfc.nasa.gov/

  18. Ozone Hole on 11/8/08

  19. When is Ozone Depletion Highest? • Spring when sunlight first hits because sunlight causes the reaction that breaks down the O3. • Remember Spring in the Antarctic is during our Fall (especially Oct). Link to EPA site of ozone hole animation

  20. Ozone Depletion Solutions • Montreal Protocol: international treaty • 1987: reduce CFC use by half by 2000 • 1990: goal to cut in half by 1995 • 1992: US law eliminated by end of 1995

  21. Ozone Depletion Reference http://www.esrl.noaa.gov/csd/assessments/2006/report.html

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