|MadSci Network: Earth Sciences|
There is a very good reason why the ozone hole is forming over the poles. There is not only the hole over Antarctica, but a smaller one over Arctica, too!
During the winter polar night, sunlight does not reach the pole. A strong wind develops called the 'polar vortex'. This has the effect of isolating the air over the polar region. Since there is no sunlight, the air within the polar vortex can get very cold. So cold that special clouds form that only exist there, and don't form anywhere else. These clouds are called Polar Stratospheric Clouds. (or PSCs for short) A chemical in these PSC clouds is very important for the breakdown of ozone. The PSC clouds accelerate the breakdown of ozone over the poles, so that a "hole" forms there, and not anywhere else. When the PSC clouds and the polar vortex goes away during the polar summer, the ozone hole begins to fill back in.
Here is a link to a homepage that has a very thorogh discussion on the ozone hole, but get someone to help you with it- it's pretty complicated. Perhaps your teacher could use it to help you understand what happens.
Try the links in the MadSci Library for more information on Earth Sciences.