Why does most stratospheric ozone depletion happen over the poles?
Studies have shown that the cold, still air over the poles during the long, dark winter causes a buildup of ice crystals high in the stratosphere. These crystals then provide a place for chlorine atoms from CFCs (chlorofluorocarbons) to cling on to and build up. When the spring comes and the area begins to heat up, the ice crystals melt and the chlorine is then released into the air. That’s when the chlorine reacts with the ozone molecules. Although there is some ozone loss over temperate and tropical regions, not as much reactive chlorine accumulates because they don’t get the same buildup of ice crystals in the stratosphere during the winter months.
