Why Antarctica 1. Strong winds blowing around the continent form what is known as the "polar vortex" - isolating the air over Antarctica from the rest of the world. 2. Polar Stratospheric clouds form. Clouds don't normally form in the stratosphere and these turn out to have the effect of concentrating the pollutants that break down the ozone.
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Why Antarctica 1. Strong winds blowing around the continent form what is known as the "polar vortex" - isolating the air over Antarctica from the rest.
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Why Antarctica1. Strong winds blowing around the continent form what is known as the "polar vortex" - isolating the air over Antarctica from the rest of the world.
2. Polar Stratospheric clouds form. Clouds don't normally form in the stratosphere and these turn out to have the effect of concentrating the pollutants that break down the ozone.
Ozone Depletion in the Stratosphere
Stratospheric ozone layer
Normal levels of ozone
Reduced levels of ozone
Dobson Units100DU=1mm1DU = .01mm
Ozone Hole?
Normally 300 Dobson Units / Equivalent to a layer of ozone 3mm thick or two pennies high
One dime or 220 Dobson Units = thin
Below 220 Dobson Units = depleted area or a “hole”
The Hole
Sept.17 2009
Ozone Depletion in StratosphereCFCs / HCFC’s / Bromine / Halons
Ozone Depletion
Quick Global Response
• Montreal Protocol stipulated a reduction in CFCs - In 1987, the Montreal Protocol was signed by many nations who agreed to reduce their emissions of CFC's to a half (of the 1987 levels) by 2000.
Full recovery of ozone levels is not likely before 2068 and regular improvement not likely until 2018.
Ozone depleting gases do appear to be trending downward but have long lifespans of 10’s to 100’s of years.
Ground level Ozone – O3
Component of photochemical SMOGPollutant in the troposphere, beneficial in
the stratosphereStrong oxidizing agentLung irritant, eye irritant1980 – 2009 30%Blue skies don’t necessary equate to clean