- (A) Ozone depletion follows an annual cycle that corresponds to the amount
of light that reaches the Antarctic. The cycle begins every year around June
when vortex winds develop in the Antarctic. Cold temperatures produced by
these winds create polar stratospheric clouds that capture floating
chlorofluorocarbons (CFCs) and other ozone-depleting compounds. For the
next two months, a reaction occurs on the cloud surface that frees the
chlorine in the CFCs but keeps it contained within the vortex. In September,
sunlight returns to the Antarctic and triggers a chemical reaction, causing
chlorine to convert ozone to oxygen gas. November brings a breakdown in
the vortex and allows the ozone-rich air to combine with the thinning ozone.
Wind currents carry this mixture over the Southern Hemisphere.
marvins-underground-k-12
(Marvins-Underground-K-12)
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