--- Gary Hildebrand <ghldbrd_at_ccp.com> wrote:
> When I was in school I was taught that the ozone layer was in a continuous
> state of degeneration/regenration, as O2 became O3 and back. Then, explain
> the ozone hole over Antarctica, which has little need for CFCs as a
> refrigerant.
This is soooo far off topic...
CFCs are distributed somewhat uniformly over the stratosphere. The reason
why Antarctica is the location of the hole is due to climate... You need
several things in proximity to "cause" the hole - A halogen ion (Chlorine
and to a lesser concentration, Bromine), a place to work and energy. The
place to work is the surface of certain sizes of ice crystals (high-altitude
clouds) that only form at temps well below -60F. Sunlight is the source
of energy.
The ozone hole opens up in Antarctica every "spring" because that's when the
sun rises (providing energy) and that's when the air is cold enough to make
the proper kinds of clouds. By late October, it's warm enough that the
clouds no longer form and the Polar Convergence dissapates, allowing the
ozone-poor air over the continent to mix with "normal" air from higher
latitudes, diluting the ozone over Australia and New Zealand, primarily.
The way the model works, it's "natural" for the hole to open and close on
an annual cycle. The real question is, how much of this is due to man-made
sources of chlorine. The direct measurements show that CFCs released at
ground level take several (18?) months to make their way to 30,000m. Since
eventually the chlorine ion forms a stable compound, each one has a vast, but
finite capacity to convert O3 to O2. The hypothesis is that more man-made
chlorine in the stratosphere means less ozone. The data I have seen suggests
that the more we pump out, the more rapidly the depletion occurs each Spring.
For the skeptical: the above is not gospel written in stone. It is my
understanding of the best explanation of the observed phenomena to date.
I am not a scientist, but I did assist researchers in data collecting
and reporting.
We now return you to your regularly scheduled topics.
-ethan
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Received on Thu Sep 14 2000 - 17:09:17 BST