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

air – ozone is colorless

Acid Deposition

Measuring Acidity

Power Plant

Acid Deposition

How Acid Deposition Develops

Effects of Acid Deposition