Re: The hole in the ozone layerat the south pole

The air of the Northern and Southern hemisphere is pretty much isolated into two 
separate parcels.
About 90% of the CFCs released were in the Northern hemisphere.
Why then isn't the Ozone hole (the springtime depletion phenomenon) more 
prominent in the North, and less prominent in the South?

It is true that the air parcels of the North and the South are largely isolated 
from one another. But there is some mixing. The average mixing time for a 
particular molecule released in the Northern hemisphere to get anywhere else in 
the Northern hemisphere (e.g. Cernobyl fallout) is a matter of 2 or 3 weeks. This 
compares with an average crossing time from North to South of between 6 months 
and a year. There is always a little casual mixing at the equator, and twice a 
year there is relatively major transfer associated with the monsoon seasons in 
each hemisphere. The average time it takes for a molecule released at the Earth's 
surface to reach the stratosphere is between 20 and 50 years. And most of the 
molecules entering the stratosphere from below do so very close to the equator. 
So as far as the molecules entering the stratosphere are concerned there is no 
North/South difference -- there has been plenty of time for thorough mixing.

Remember that in order to help cause ozone destruction in the polar phenomenon, a 
CFC molecule must rise from the surface into the stratosphere to at least 30 km 
altitude, break up into smaller free radicals, and then be stored in the 
stratosphere as hydrogen chloride or chlorine nitrate until it finds its way to 
the polar regions in the stratosphere.

The reason that the ozone hole forms over the Antarctic rather than the Arctic 
has to do with climatic differences which ultimately tie in with the different 
surface geography in the two polar regions. The Antarctic lower stratosphere is 
typically about 5 to 8 deg C colder than the Arctic.

A good series of ozone links can be found at 
CRC for Southern Hemisphere Meteorology

Response:

Re: The hole in the ozone layerat the south pole
we a re told that the hole in the ozone layer at the south pole is caused 
by the release of cfc gas from airosols and fridges . Most of these would 
be in the northen hemaphere ,so due to this the hole sould be at the north 
pole, because we are told the the nouth and south hemaphese are mostly 
seperated ie cebinol radiation from the ussr stayed in the nonth ,
i would like to know 
with thanks 
Trevor Ridgley


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