1. Botkin and Keller Environmental Science 5e Chapter 25 Ozone Depletion

2. Botkin and Keller Environmental Science 5e Ozone A form of oxygen in which three atoms of oxygen occur together. Chemically active and has a short average lifetime in the atmosphere Forms a natural layer high in the atmosphere that protects us from harmful ultraviolet radiation from the sun A pollutant when present in the lower atmosphere

3. Botkin and Keller Environmental Science 5e

4. Botkin and Keller Environmental Science 5e Ultraviolet Radiation and Ozone Ozone Shield: Stratospheric ozone layer that absorbs ultraviolet radiation Ultraviolet A: –Longest length, least energetic –Can cause some damage to living cells –Transmitted to earth Ultraviolet B: –Intermediate wavelength –Cause of Ozone Problem Ultraviolet C: –Shortest wavelength/ Most energetic

5. Botkin and Keller Environmental Science 5e

6. Botkin and Keller Environmental Science 5e Measurement of Stratospheric Ozone Dobson Unit –Commonly used to measure the concentration of ozone

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9. Botkin and Keller Environmental Science 5e Ozone Depletion and CFCs Ozone depleted due to emission of CFCs CFCs are stable and have a long residence time in the atmosphere In stratosphere, release chlorine and enter into catalytic chain reaction- depletes ozone More UV radiation reaches lower atmosphere

10. Botkin and Keller Environmental Science 5e

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15. Botkin and Keller Environmental Science 5e Polar Stratospheric Clouds Clouds that form in the stratosphere during the polar winter Polar Vortex –Artic air masses that in the winter become isolated from the rest of the atmosphere and circulate about the pole –Rotates counterclockwise because of the rotation of the earth in the Southern Hemisphere

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18. Botkin and Keller Environmental Science 5e Management Issues Key issue is whether ozone depletion is natural or human-induced Montreal Protocol Collection and Reuse of CFCs Substitutes for CFCs –HFCs and HCFCs Short-Term Adaptation to Ozone Depletion