Atmospheric Structure and Ozone

The ozone layer in the stratosphere absorbs solar UV-B (280-320 nm) which is the most harmful part of the ultraviolet. Thus it acts as protector gas for plants, animals by absorbing harmful UV radiation in the stratosphere and as pollutant around the ground level. Nature intended that the stratospheric ozone layer would block the sun's harmful ultraviolet rays.. (CFC), which contains chlorine, an ozone destroyer.

The concentration of ozone varies with an altitude of the atmospheric layers. Ozone is basically stratospheric gas. The reaction of the oxygen with the UV radiations result in the formation of the ozone layer. Peak concentration, an average of 8 molecules per million molecules occur above the altitude of 30kms from the earth's surface which is roughly 20 miles. This is the height that corresponds to the stratosphere.

The high altitude supersonic aircraft flying in stratosphere zone emit nitrous oxides which can destroy ozone significant quantity being highly reactive. Aerosols are tiny particles in the air resulting from the burning of fossil fuels, emission from cars and factories are also causal factors of aerosols. It may be referred to the spray cans that release chlorofluorocarbons which cause the breakdown of ozone Into oxygen once these compound reach the stratosphere.

'Good ozone' is found in the upper part of the atmosphere called the stratosphere and it act as a shield by absorbing ultraviolet radiations from the sun. UV rays are, highly injurious to living organisms. 'Bad ozone' is formed in the lower part of atmosphere called troposphere and it harms plants and animals.

Ozone-depleting substances (ODS) are substances that react with ozone present in the stratosphere and destroy the same. The major Ozone-depleting substances are chlorofluorocarbons (14% of total depletion), nitrogen oxides (3.5% depletion), sulphur dioxide, halon, carbon tetrachloride, methyl chloroform, chlorine, etc.

Ozone depletion is occurring widely in the stratosphere, particularly marked over the Antarctic region.

An ozone layer, present in the stratosphere, reflects the ultraviolet rays emitted by the sun and thus it prevents us from skin diseases and mutation.

The main factor responsible for the depletion of ozone layer is addition of Cl in the atmosphere.
Each Cl atom can destroy as many as 100,000 ozone molecules. Cl atoms comes from chlorofluorocarbons.

The depletion of the ozone layer was noticed in the year 1980.
The large scale destruction of the stratospheric ozone first came into focus in 1987 through the experiments in antarctica.

When the destruction of the ozone layer increases, the amount of harmful ultraviolet radiation increases.
Note:
Ozone layer acts as natural sun block and shields us from the UV radiations of the sun which are dangerous to living organisms.
The ozone molecules absorb ultraviolet rays between 310 to 200 nm wavelength.
Ozone absorbs UV radiation to give back oxygen. Thus, the ozone layer acts as a screen and prevents the harmful radiations from reaching the surface of earth.