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Name: Unknown
Status: N/A
Age: N/A
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Date: Before 1993


Question:
What is the mechanism by which CFC's (Chloral Fluoral Carbon) generated at or near sea level by "non-natural" sources effect high level ozone at or near the South Pole? Most explanations about this issue do not fully explain how a dense, heavy molecule generated at moderate latitudes effect only ozone at high levels but not at sea level. If CFC's are so unstable that they deteriorate, does not Pascal's law of fluid dynamics take over? In that case should not levels of ozone be depleting evenly throughout our (almost) perfectly fluid atmosphere?



Replies:
This is a very detailed question, some references that may be able to help are: "Chemistry of Atmospheres" by Richard P. Wayne (Clarendon Press, Oxford, 1991). There is a whole chapter on ozone depletion and the "hole" over Antarctica. First, it seems that there is some very unusual chemistry going on above the Antarctic! The weather patterns there conspire to make this happen. First, the low temperatures lead to the formation of polar stratospheric clouds, which are high-altitude. The second is that as air cools and descends towards the poles in the winter, a vortex at the polar region is formed, with a westerly circulation at the South Pole. This vortex has a very cold core, and anything that gets dumped into its interior, such as atmospheric chlorine radicals, (i.e., ClO) stays there for a long time. This vortex comes and goes seasonally; it breaks down in November as the air gets warmer. In other words, the vortex acts as a giant "reaction chamber" in which exotic reactions (which can only happen at low temperatures) have all the time in the world to happen.

Topper



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