What is mean by ozone hole? Discuss the process behind the destruction of ozone layer and provide the reasons for its recovery in the arctic region. (200 Words)
Refer - The Indian Express
Enrich the answer from other sources, if the question demands.
IAS Parliament 5 years
KEY POINTS
Ozone Hole
· The ‘ozone hole’ is not really a hole — it refers to a region in the stratosphere where the concentration of ozone becomes extremely low in certain months.
· The ‘ozone holes’ most commonly talked about are the depletions over Antarctica, forming each year in the months of September, October and November, due to a set of special meteorological and chemical conditions that arise at the South Pole, and can reach sizes of around 20 to 25 million sq km.
Process of destruction of ozone layer
· The ozone depletion process begins when CFCs and other ozone-depleting substances (ODS) are emitted into the atmosphere.
· Winds efficiently mix the troposphere and evenly distribute the gases. CFCs are extremely stable, and they do not dissolve in rain. After a period of several years, ODS molecules reach the stratosphere, about 10 kilometers above the Earth's surface.
· Strong UV light breaks apart the ODS molecule. CFCs, HCFCs, carbon tetrachloride, methyl chloroform, and other gases release chlorine atoms, and halons and methyl bromide release bromine atoms .
· It is these atoms that actually destroy ozone, not the intact ODS molecule. It is estimated that one chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere.
Reasons for ozone hole recovery
· The ozone hole’s closing was because of a phenomenon called the polar vortex, and not because of reduced pollution levels due to Covid-19 lockdowns around the world.
· Increase in temperature levels slightly.
Nikhila Krishna 5 years
During September 2019 the ozone hole over the Antarctic has been smallest observed since 1972
Ozone hole:-
* Depletion of the ozone layer over the atmosphere(in Stratosphere) over the earth will cause thin the layer is called ozone hole.
*Manufactured chemicals thins the ozone, in which the most dominant factor is CFC's(chlorofluorocarbons)
Process of the destruction of Ozone alter:-
* The depletion happens everywhere beyond tropics but it's severe in polar region.because of larger variation in getting sunlight and in the interest of the time in the dark without sunlight.
* extremely low-temperature cause formation of polar stratospheric clouds.
*The clouds are made of ice crystals which provide a surface for many chemical reactions.
*Ozone-depleting substances reacting the stratosphere .they CFC's subjects to a higher level of UV radiation that decomposes them and releases atomic chlorine.
*Atomic chlorine reacts with ozone and gives out Cl+O3---ClO+O2.
*Cl gets removed once it has converted an ozone molecule to oxygen molecule but then it's regenerated through the reaction of carbon monoxide with an oxygen atom as CLO+O----Cl+
* the net reaction of the above two sets is O3+O ---2O2
*net result of two reactions is ozone depletion.
Recovery in the Arctic region:-
*UN had already hailed the success of MONTREAL PROTOCOL, which banned the depleting chemicals. we want the introduction and implementation of such efforts
* The source countries should identify and there should be stringent laws to make them come out of it
IAS Parliament 5 years
Good attempt. Keep Writing.
Padala veera venkata satyanarayana 5 years
Sir.. please mention my mistakes..
IAS Parliament 5 years
Importance of ozone layer and definition of polar vortex are not needed. Try to include about the role polar stratospheric clouds. Keep Writing.
