Ozone Depletion

Ozone is a gas made of oxygen atoms.
–O2 - two oxygen atoms - ordinary common or garden oxygen
–O3 - three oxygen atoms - Ozone

Most of the ozone on earth isn't on earth at all, but in the layer of the earth's atmosphere called the stratosphere.

Why is a ozone hole a problem?
Ozone in the stratosphere benefits to life on earth
–absorbs the harmful ultra-violet light from the sun while letting other light wavelengths through.

Too much ultra-violet light can result in:
–Skin cancer Eye damage such as cataracts
– Immune system damage
–Reduction in phytoplankton in the oceans that forms the basis of all marine food chains including those in Antarctica.
–Damage to the DNA in various life-forms So far this has been as observed in Antarctic ice-fish that lack pigments to shield them from the ultra-violet light (they've never needed them before)
– Probably other things too that we don't know about at the moment.


Why does a ozone hole form over Antarctica?
The ozone hole is caused by the effect of pollutants in the atmosphere destroying stratospheric ozone. During the Antarctic winter something special happens to the Antarctic weather.
–Firstly, strong winds blowing around the continent form "polar vortex" - this isolates the air over Antarctica from the rest of the world.
–Secondly, special clouds form called Polar Stratospheric Clouds.


















Polar Stratospheric Cloud, seen from the NASA DC-8 on 14 January 2003
(photograph by Paul Newman, GSFC).
























Assimilated total ozone September 25th, 2006.