The ozone layer

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The ozone layer

  1. 1. University of Salahaddin Faculty of science Department of Chemistry
  2. 2. THE OZONE LAYER What is it? Where is it? Why is it important to life on Earth? How are we as humans affecting it?
  3. 3. What is the ozone layer?What is the ozone layer? The ozone layer is aThe ozone layer is a layer of gas consistinglayer of gas consisting of Oof O33 molecules, calledmolecules, called ozone, that formsozone, that forms when free Oxygenwhen free Oxygen molecules bond to Omolecules bond to O22 molecules.molecules.
  4. 4. OzoneOzone Ozone is a moleculeOzone is a molecule consisting of oxygenconsisting of oxygen atoms.atoms. Ozone gas can beOzone gas can be created or destroyedcreated or destroyed by the sun’sby the sun’s UltraViolet rays asUltraViolet rays as shown in the pictureshown in the picture to the right.to the right.
  5. 5. Where is the ozone layer?Where is the ozone layer? The ozone layer is aThe ozone layer is a protective layer of gasprotective layer of gas molecules locatedmolecules located within the stratosphere.within the stratosphere. Ozone gas also existsOzone gas also exists in the troposphere andin the troposphere and at ground level, butat ground level, but most is located withinmost is located within the stratospheric layerthe stratospheric layer shown to the right.shown to the right.
  6. 6. Earth’s AtmosphereEarth’s Atmosphere
  7. 7. Why is it important to life onWhy is it important to life on Earth?Earth? On a daily basis, the sun radiates its energy towardOn a daily basis, the sun radiates its energy toward Earth. One form of this energy is UltraViolet radiation,Earth. One form of this energy is UltraViolet radiation, also known as UV rays.also known as UV rays. UV rays are relatively high energy waves that provideUV rays are relatively high energy waves that provide Earth with the warmth it needs to support life as weEarth with the warmth it needs to support life as we know it.know it.
  8. 8. Ultra-Violet RadiationUltra-Violet Radiation UV rays penetrateUV rays penetrate the Earth’sthe Earth’s atmosphere at 3atmosphere at 3 slightly differentslightly different wavelengths calledwavelengths called UV-A, UV-B, andUV-A, UV-B, and UV-C rays.UV-C rays.
  9. 9. So, why is the ozone layerSo, why is the ozone layer important to life on Earth?important to life on Earth? The stratospheric ozoneThe stratospheric ozone layer completely stopslayer completely stops the penetration of UV-Cthe penetration of UV-C rays and eliminatesrays and eliminates most of the UV-B rays.most of the UV-B rays. Therefore, the ozoneTherefore, the ozone layer protects life onlayer protects life on Earth from the harmfulEarth from the harmful effects of solar radiationeffects of solar radiation on a daily basis.on a daily basis.
  10. 10. So what might life be like withoutSo what might life be like without the ozone layer?the ozone layer?
  11. 11. How are we as humans affectingHow are we as humans affecting the ozone layer?the ozone layer? Since 1928, Chlorofluorocarbons have beenSince 1928, Chlorofluorocarbons have been produced, originally as nonflammableproduced, originally as nonflammable refrigerants for use in refrigerators, andrefrigerants for use in refrigerators, and eventually for use in fire extinguishers, dryeventually for use in fire extinguishers, dry cleaning agents, pesticides, degreasers,cleaning agents, pesticides, degreasers, adhesives, and as propellants for aerosoladhesives, and as propellants for aerosol products.products. As these CFCs have been released into theAs these CFCs have been released into the atmosphere, the level of ozone in theatmosphere, the level of ozone in the stratosphere has decreased.stratosphere has decreased. CFCs have an estimated lifespan of moreCFCs have an estimated lifespan of more than 100 years.than 100 years.
  12. 12. CFCs and OzoneCFCs and Ozone
  13. 13. And the effects of all those CFCs...And the effects of all those CFCs...
  14. 14. So what about the hole in theSo what about the hole in the ozone layer?ozone layer? October 1979 October 2007
  15. 15. The Ozone HoleThe Ozone Hole Since the 1970’s the ozone hole hasSince the 1970’s the ozone hole has been increasing in size over thebeen increasing in size over the Antarctic.Antarctic. For the first time, in September of 2000,For the first time, in September of 2000, the ozone hole became so large itthe ozone hole became so large it actually left populated areas of southernactually left populated areas of southern Chile fully exposed to the effects of theChile fully exposed to the effects of the Sun’s UV rays.Sun’s UV rays.
  16. 16. Chile’s Ozone HoleChile’s Ozone Hole
  17. 17. How does ozone depletion affectHow does ozone depletion affect global warming and ultimatelyglobal warming and ultimately climate change?climate change? As ozone levels in the stratosphere areAs ozone levels in the stratosphere are depleted, more solar radiation penetrates thedepleted, more solar radiation penetrates the Earth’s atmosphere.Earth’s atmosphere. This affect results in an increase in solarThis affect results in an increase in solar radiation reaching the Earth’s surface addingradiation reaching the Earth’s surface adding to an increase in surface temperature.to an increase in surface temperature. In turn, global warming actually results in aIn turn, global warming actually results in a warming of the troposphere, but a cooling ofwarming of the troposphere, but a cooling of the stratosphere, hindering the ozone layer’sthe stratosphere, hindering the ozone layer’s natural chemistry for repairs.natural chemistry for repairs.
  18. 18. So what are we doing about it?So what are we doing about it? After the discovery of ozone depletion in the late 1970’s, manyAfter the discovery of ozone depletion in the late 1970’s, many countries agreed that something must be done worldwide tocountries agreed that something must be done worldwide to stop the production of man-made, ozone harmful products.stop the production of man-made, ozone harmful products. The international community adopted the Vienna Convention inThe international community adopted the Vienna Convention in 1985 followed by the Montreal Protocol in 1987.1985 followed by the Montreal Protocol in 1987. The latest reports confirm that it has led to the phasing out ofThe latest reports confirm that it has led to the phasing out of about 95% of the consumption of ozone-depleting substancesabout 95% of the consumption of ozone-depleting substances (ODS) listed in the agreement. In turn, this has led to the(ODS) listed in the agreement. In turn, this has led to the prospect of the ozone layer recovering by 2050 to 2075.prospect of the ozone layer recovering by 2050 to 2075. Furthermore, the phasing out of ozone-depleting substancesFurthermore, the phasing out of ozone-depleting substances has helped to fight climate change since many of thesehas helped to fight climate change since many of these chemicals are also powerful greenhouse gases. According to achemicals are also powerful greenhouse gases. According to a recent study, the phasing out of substances under the Protocolrecent study, the phasing out of substances under the Protocol led to more reductions in greenhouse gases than what isled to more reductions in greenhouse gases than what is foreseen under the Kyoto Protocol.foreseen under the Kyoto Protocol.
  19. 19. What can we do, as concernedWhat can we do, as concerned citizens, to ensure that ourcitizens, to ensure that our children have a viable planet tochildren have a viable planet to inhabit?inhabit?

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