OZONE,ITS DEPLETION AND CAUSES OF OZONE LAYER DEPLETIONby Meena Pandey | 16-09-2019 19:40 |
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Ozone Contribute a small percentage of about 0.00006% of total air volume, found in upper atmosphere and it is not uniformly distributed. Mostly concentrates on 30-60 km from earth surface called ozonosphere. O3 is an efficient absorber of ultraviolet radiation and help to protect the biosphere. There is a maximum concentration of ozone, a vital gas, between 30 and 60 km above the surface of the earth. The formation of ozone takes place in the upper stratosphere when an oxygen molecule is broken into two atoms by UV radiation and that free unstable atoms combine with oxygen molecules to form ozone. However, the emission of nitrogen oxide causes deterioration of ozone layer with the resultant serious damage to flora and fauna. Here, temperature increases with height at the rate of 5oC/km. Because of the preponderance of chemical process, this layer is also called chemosphere. Anthropogenic emissions of ozone-depleting gases lead to marked changes in surface climate, through the radiative and dynamical effects of the Antarctic Anthropogenic emissions of carbon dioxide and other greenhouse gases have driven and will continue to drive widespread climate change at the Earth's surface. But surface climate change is not limited to the effects of increasing atmospheric greenhouse gas concentrations ozone hole. The stratospheric ozone is being destroyed by a group of manufactured chemical . These chemicals are also called Ozone depleting Substances(ODS).ODS are very stable ,non-toxic and environmentally safe in the lower atmosphere. Their stability allows them to float up, intact to the atmosphere .Once there, they are broken apart by the intense ultra-violet light. They demolish ozone at an alarming rate. A single molecule can break thousands molecule of ozone. The main ODS are CFCs, which is responsible for 80% stratospheric ozone layer depletion. CFCs are used as a coolant in refrigerators, fridges and air conditioners in buildings. It is also found in industrial solvents, dry cleaning agents and hospital sterilants. Halons are used in some fire extinguishers which cause greater damage to the ozone layer than CFCs from automobile and air conditioners, Methyl chloroforms are mainly used in industry for vapor decreasing , some aerosols, cold cleaning ,adhesives and cleaning processes. HCFCs are become major ¡°transitional¡± for CFCs. |