Environment and Ecology Research | 2019
Contribution of Excited Ozone and Oxygen Molecules to the Formation of the Stratospheric Ozone Layer
Abstract
The absorption of UV, visible and near IR radiation by O 3 produces transient, electronically excited O 3 . The absorption of thermal IR radiation ( = 9.065, 9.596 and 14.267 µm) produces vibrationally excited O 3 molecules. Thermal absorption is likely the main factor in the self-decay of O 3 . Photoexcitation of ground state by IR and red light radiation produces singlet oxygens and . Chemical reactions in the stratosphere produce them as well. When reacting with ozone, singlet oxygen produces O ( 3 P) and . By doing so, they tend to maintain the prevailing ozone concentration and are thereby important for the stability of the ozone layer. During the daytime, O( 1 D), and reach their maximum concentrations at altitudes of 45 to 48 km. This manifests fast ozone turnover which generates the maximum stratospheric temperature at those particular altitudes. During the night-time, the self-decay of ozone and absorption of light from the nightglows, moon and stars by O 3 and O 2 generates so much heat that the stratospheric temperature decreases by only a couple of degrees. Being a heavier gas than O 2 and N 2 , ozone lacks buoyancy in the atmosphere, and it starts to descend immediately when formed. Chapman calculated that ozone in the stratosphere would descend 20 m per day. At the North and South Poles, during the four to six months of darkness in the winter, ozone descends by 2.4 to 3.6 km. This descent is likely the main reason for the stratospheric ozone depletion above the poles during winter.