An atmospheric layer that contains a high proportion of oxygen that exists as ozone. The ozone is created by a series of processes beginning with the splitting up of the oxygen molecule to single oxygen atoms. It acts as a filtering mechanism against incoming ultraviolet radiation.
The ozone layer was discovered by Charles Fabry in 1913. In 1985 a British expedition to the Antarctic discovered a hole in the ozone layer above the south pole.
The layer extends from about 12 to 40 km. The ozone concentration reaches a maximum between about 20 and 25 km.
The ozone layer is being depleted by human emissions of chlorine and bromine compounds. Every year, during the Southern Hemisphere spring, a very strong depletion of the ozone layer takes place over the Antarctic region, also caused by human-made chlorine and bromine compounds in combination with the specific meteorological conditions of that region.