Ozone Layer


Ozone shield or ozone layer is a part of earth’s stratosphere that absorbs most of ultraviolet (UV) radiation from the sun. It is made up of high concentration of ozone (o3) as compared to other regions of the atmosphere. The ozone layer encompasses less than ten parts per million of ozone whereas the average concentration of ozone in the earth’s atmosphere is about 0.3 parts per million. The ozone layer is mainly located in the stratosphere’s lower part from approximately 30-20 kilometres above the earth though the thickness differs geographically and seasonally.

The ozone layer absorbs 99-97 percent of the medium frequency ultraviolet light from the sun that would result to damaging of the exposed forms of life near the surface. There are two forms of ozone depending on where it is in the atmosphere; stratospheric (good) and tropospheric (bad) ozone layer. Tropospheric ozone layer is closest to the earth and it poses as an air pollutant that is dangerous to breathe and results in damages to trees, vegetation and crops whereas the stratospheric ozone layer serves as a life protector and is furthest from the earth. The United Nations Assembly has appointed 16th September as the International day for ozone layer preservation.

The importance of ozone layer to Earth and life

The ozone layer is crucial to the earth as it absorbs most of sun’s ultraviolet (UV) radiation hindering most of it from reaching the surface of the Earth. UV spectrum radiation has wavelengths slightly shorter than those of visible light. UV radiation that has wavelengths between 315 and 280 nanometers is known as UV-B, and it results in damages to almost all kinds of life. By taking in most of UV-B radiation before it can even reach the surface of the earth, the ozone layer protects the Earth from the harmful effects of radiation.

In addition, stratospheric ozone also affects the distribution of temperature of the atmosphere, therefore, playing a significant role in earth’s climate regulation.

The causes of ozone layer depletion

Ozone layer depletion is as a result of the release of ozone-depleting substances (ODS) and other chlorofluorocarbons (CFCs) that were widely used as insulating foams, solvents and refrigerants. Although air is lighter than CFCs, CFCs are carried into the stratosphere through a process that can take a period of 2 to 5 years. After CFCs reaches the stratosphere, the sun’s ultraviolet radiation causes them to dismantle releasing chlorine atoms that react with ozone, initiating ozone’s destruction chemical cycles that eventually leads to ozone layer depletion.

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