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The Chapman Cycle

The Chapman Cycle. l ≤. l ≤. A steady state condition. 2.6. Biological Effects of Ultraviolet Radiation. The consequences depend primarily on : The energy associated with the radiation. The length of time of the exposure. The sensitivity of the organism to that radiation.

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The Chapman Cycle

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  1. The Chapman Cycle l≤ l≤ A steady state condition 2.6

  2. Biological Effects of Ultraviolet Radiation • The consequences depend primarily on: • The energy associated with the radiation. • The length of time of the exposure. • The sensitivity of the organism to that radiation. The most deadly form of skin cancer, melanoma, is linked with the intensity of UV radiation and the latitude at which you live. An Australian product uses “smart bottle” technology; bottle color changes from white to blue when exposed to UV light. 2.7

  3. How CFCs Interact with Ozone First, UV radiation breaks a carbon-halogen bond: Photon (l < 220 nm) + CCl2F2 .CClF2 + Cl. (free radicals) 2.9

  4. The chlorine radical attacks an O3 molecule: 2Cl. + 2O3 2ClO. + 2O2 Then two chlorine monoxide radicals combine: 2 ClO. ClOOCl The ClOOCl molecule then decomposes: UV photon + ClOOCl ClOO. + Cl. ClOO. Cl. + O2 The Cl. radicals are free to attack more O3 The Cl. radicals are both consumed and generated; they act as catalysts The net reaction is: 2 O3 3O2 2.9

  5. Experimental analyses show that as ClO. concentrations increase, ozone concentration decreases. 2.9

  6. Antarctic ozone map for 11 September 2011

  7. Largest Ozone Hole Ever Observed 9-24-2006

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