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During which months does the Antarctic ozone hole usually appear?
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Ozone depletion
The Antarctic ozone hole reaches its maximum extent in October of each year. On October 7, 2021, when this image was captured, the Antarctic ozone hole spanned 24.8 million square km (9.6 million square miles).
The Antarctic ozone hole typically appears during the Southern Hemisphere's springtime, which spans the months of September to November.1
During the preceding winter, the polar vortex isolates the air over Antarctica, allowing temperatures to drop low enough for the formation of polar stratospheric clouds. When sunlight returns to the region in early spring, it triggers chemical reactions on these cloud particles that release reactive chlorine and bromine, leading to the rapid destruction of ozone. This depletion process continues until the polar vortex breaks up, which generally occurs in November.1