The springtime decline in total ozone over Antarctica produces what is widely known as the ΓÇ£ozone holeΓÇ¥. As summer approaches, the total ozone increases and the ΓÇ£holeΓÇ¥ disappears.
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The images at the right clearly show that since 1979, the protective ozone layer has declined in concentration and area. In fact, the ozone hole has grown so much over the years that it is much larger than the entire Antarctic continent, and is now approximately the size of North America. The color bar and numbers represent Dobson Units, a measurement of total column ozone. Red indicates high levels and purple indicates low levels.
Stratospheric clouds over Antarctica contain ice particles not found at warmer latitudes. Reactions occurring on the surface of the ice particles speed the ozone destruction caused by chlorine atoms from industrial chemicals, mainly the chlorofluorocarbons (CFCs) used in refrigeration and other applications.
