Ozone Layer A layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). Absorbs 97–99% of the suns high frequency ultraviolet light, which is potentially damaging to life on earth.
Ozone Layer (cont’d) It is mainly located in the lower portion of the stratosphere from approximately 13 km to 20 km above Earth, though the thickness varies seasonally and geographically.
Ozone Layer (cont’d) The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. Its properties were explored in detail by the British meteorologist G. M. B. Dobson, who developed a simple spectrophotometer (the Dobson meter) that could be used to measure stratospheric ozone from the ground.
Ozone Layer (cont’d) Between 1928 and 1958 Dobson established a worldwide network of ozone monitoring stations which continues to operate today. The "Dobson unit", a convenient measure of the columnar density of ozone overhead, is named in his honour.
Origin of Ozone The photochemical mechanisms that give rise to the ozone layer were discovered by the British physicist Sidney Chapman in 1930.
Ultraviolet Light and Ozone The ozone is vitally important because it absorbs the biologically harmful UV radiation coming from the sun. UV radiation is divided into 3 categories UV-A (400–315 nm) UV-B (315–280 nm) UV-C (280–100 nm)
Ozone Depletion The ozone layer can be depleted by free radical catalysts, including nitric oxide (NO), nitrous oxide (N2O), hydroxyl (OH), atomic chlorine (Cl), and atomic bromine (Br). The concentrations of chlorine and bromine have increased markedly in recent years due to the release of large quantities of man- made organohalogen compounds, especially chlorofluorocarbons (CFCs) and bromofluorocarbons.