A meteorological phenomenon that occurs in the polar regions, most pronounced in the region of the South Pole. It is of great interest as it is one of the primary reasons why there will continue to be a huge ozone hole right over Antarctica every spring for at least the next 300 years, provided our use of CFC's doesn't continue to taper off.
During polar winter, the topography and circular shape of the Antarctic continent causes an extremely cold whirlpool of stagnant air to form over it during the six months of darkness. This is the polar vortex. The atmospheric temperatures there drop so low that polar stratospheric clouds form, which greatly accelerate the process of ozone destruction once there is sunlight again in early spring.
A similar process also occurs over the North Pole, however due to the presence of many irregular land masses around that pole, it is much weaker, and the corresponding ozone depletion much less. Unfortunately, global warming serves to increase the strength of the northern polar vortex and consequently the size of the ozone hole there.