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The ozone layer and its depletion

This is a school project on the ozone layer made by my daughter aakanksha.

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The ozone layer and its depletion

  3. 3. INDEX TOPIC Pg no.Layers of the Atmosphere 4-5The Sun’s Utraviolet Rays 6-8The Ozone Layer 9 3
  4. 4. LAYERS OF THE ATMOSPHEREThe atmosphere is divided into five layers. It is thickestnear the surface and thins out with height until iteventually merges with space.1) The troposphere is the first layer above the surface andcontains half of the Earths atmosphere. Weather occurs inthis layer.2) Many jet aircrafts fly in the stratosphere because it isvery stable. Also, the ozone layer absorbs harmful raysfrom the Sun.3) Meteors or rock fragments burn up in the mesosphere. 4
  5. 5. 4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits. 5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.Ozone layer 5
  6. 6. THE SUN’S ULTRAVIOLET RAYS The sun emits energy over a broad spectrum of wavelengths: visible light that you see infrared radiation that you feel as heat ultraviolet (UV) radiation that you can’t see or feel. UV radiation has a shorter wavelength and higher energy than visible light. 6
  7. 7. It affects human health both positively andnegatively. Short exposure to UVB radiation generates vitaminD, but can also lead to sunburn depending on anindividual’s skin type.Fortunately for life on Earth, our atmosphere’sstratospheric ozone layer shields us from most UVradiation 7
  8. 8. Damage to the ozone layer can cause the following:Skin cancerCataractsSuppression of the immune systemPremature aging of the skinSince the benefits of sunlight cannot be separatedfrom its damaging effects, it is important tounderstand the risks of overexposure, and takesimple precautions to protect yourself. 8
  9. 9. THE OZONE LAYERThe ozone layer is a deep layer in thestratosphere, encircling the Earth,that has large amounts of ozone in it. The layer shields the entire Earthfrom much of the harmful ultravioletradiation that comes from the sun.For nearly a billion years, ozonemolecules in the atmosphere haveprotected life on Earth from theeffects of ultraviolet rays. 9
  11. 11. INDEXTOPIC Pg no.The Ozone Hole and Its Causes 12-13Observations on Ozone Layer 14DepletionObservation 1 15Observation 2 17Misconceptions about the Ozone Layer 18DepletionBibliography 19 11
  12. 12. THE OZONE HOLE AND ITS CAUSES Recently, chlorofluorocarbons (CFCs) were used a lot in industry and elsewhere to keep things cold and to make foam and soaps. Strong winds carry CFCs up into the stratosphere where UV radiation breaks them apart, releasing chlorine atoms. Each chlorine atom can attack and break apart (destroy) as many as 100,000 ozone molecules during the time it is in the stratosphere. 12
  13. 13. The chlorine from CFCs reduces (depletes) the amount ofozone in the stratosphere.Other ozone-eating chemicals are pesticides such as methylbromide, halons used in fire extinguishers, and methylchloroform used in businesses. 13
  14. 14. OBSERVATIONS ON OZONE LAYER DEPLETION There are many observations on the ozone layer. The following are a few observations: 14
  15. 15. OBSERVATION 1Scientists did predict that ozone depletion shouldpeak around year 2010. As world-wide controls reduce the release of CFCsand other ozone-eating substances, nature will repairthe ozone layer.By year 2065 stratospheric ozone should return to theamount present in 1980.Until then, we can expect higher levels of UVradiation at the Earths surface. We need to take care to avoid the bad health effectsthat could result from too much UV radiation. 15
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  17. 17. OBSERVATION 2Most countries have seen the threats created byozone depletion and agreed to a treaty called theMontreal Protocol.This Protocol will help humans to stop making andusing ozone-eating chemicals. 17
  18. 18. MISCONCEPTIONS ABOUT THE OZONE LAYER DEPLETION COMMON MISTAKE FACTGlobal warming is caused The ozone layer protects theby the ozone hole which Earth from the Sun’s harmful UV rays. Hole in the ozonewas created by chemicals layer has been caused bylike CFC etc. chemicals released by humans.CFC’s are “too heavy” to CFC’s are commonly believedreach the stratosphere. to be heavy. But atmosphere gases are not sorted by weight. The wind mixes the gases and they reach the 18 atmosphere.
  19. 19. PROTECTING THE OZONE LAYER The ozone layer must be protected. For this the use of CFC’s has to be stopped. We must buy products that are labelled “ozone friendly” or “ CFC free”. Substitutes for CFC’s should be used. HCFC’s are substitutes for CFC’s. Let us all take a step ahead and save the ozone layer. 19
  20. 20. BIBLIOGRAPHY 20