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Why does ozone destruction slow after the Antarctic polar vortex breaks up?

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ozone depletion — 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).

Ozone destruction slows after the Antarctic polar vortex breaks up because the vortex acts as a containment mechanism that isolates the air over Antarctica from the rest of the atmosphere.12

During the winter, the polar vortex creates extremely cold conditions that allow for the formation of polar stratospheric clouds (PSCs). Chemical reactions on the surfaces of these cloud particles convert less-reactive chlorine compounds into highly reactive forms, such as molecular chlorine, which accumulate throughout the polar night.12

When spring returns and sunlight reaches the region, it breaks these molecules into single chlorine atoms that actively destroy ozone molecules. The vortex maintains this isolated, cold environment, facilitating the destruction process. Once the polar vortex breaks up—typically in November—the isolated air mass mixes with warmer, ozone-rich air from outside the region, effectively ending the conditions necessary for the rapid, localized chemical destruction of ozone.12