Focus on ozone

Looking to plug holes in our knowledge about the ozone hole, some 350 scientists from around the world are studying the Arctic atmosphere this winter to understand chemical changes in the stratosphere (30,000 to 180,000 feet up) brought about by solar radiation.

Ozone acts as a protective layer against the sun’s ultraviolet radiation. As temperatures fall during winter, polar stratospheric clouds can form. A series of chemical reactions on the surface of cloud particles frees up chlorine and bromine, which react with sunlight to cause ozone destruction when the sun returns in spring.

The sources of chlorine and bromine are human-produced chlorofluorocarbons (CFCs) and halocarbons.

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