Ozone layer and greenhouse

Ozone is a very vital gas in the atmosphere. It is made up of three atoms of oxygen while ordinary oxygen is made up of only two (diatomic).the atmosphere provides a thermal blanket and radiation shield to earth. In the upper atmosphere, 15-50 km above the earth, oxygen and ozone absorbs much of the incoming short-wave radiations. These are ultraviolet, X- and gamma-rays which are very harmful to living organisms, damaging their genetic material. The studies say it has been estimated that a 5% reduction in stratospheric ozone would lead to a 7.5-15% increase in ground level UV radiation in USA.

The ozone layer present in the atmosphere is extremely important for all the living things. It is due to the presence of ozone layer in it that the atmosphere protects the living beings form harmful radiations. The ultra-violet radiations emitted by the sun are extremely harmful to the living things including human beings. The ultra-violet radiation emitted by the sun is short wavelength due to which they can penetrate deep into our body. The ultra violet radiation destroys the organic molecules which are necessary for life and can cause serious disease like skin cancer. Ozone layer present in the upper atmosphere absorbs harmful ultra violet radiation emitted by the sun protects human health and crop plants from many ill-effects which could be caused by these radiations.

In human beings, UV rays cause various disease like cataract (disease of eye lens becomes opaque causing blindness), sun burn, premature aging, skin cancer and inflammatory disease. The UV ray hampers the growth and development of plants and animals. The productivity of crops is reduced. Various species of plants and animals may extinct. As more UV ray enters the earth because of ozone layer depletion, the heat accumulates more and greenhouse effect increases. As a result, temperature of the earth increases.

To control the depletion of ozone layer, the production and use of chlorofluorocarbon should be banned. The alternatives for the CFCs should be developed. Release of oxides and nitrogen should be avoided and people should be educated to bring awareness about the protection of ozone.

Photosynthesis takes carbon dioxide out of the air. Respiration and burning put carbon dioxide into the air. These processes naturally balance each other. So, the amount of carbon dioxide in the air stays about the same. But humans are now upsetting the balance. We are burning more and more fossil fuels. Extra carbon dioxide is going into the atmosphere. The amount of carbon dioxide in the air has gone up by one quarter since pre-industrial times. This carbon dioxide behaves rather like the glass of the green house. It lets the sun’s ray through on the surface of the earth but stops the heat from escaping.  So, surface of the earth getting warmer. This is called greenhouse effect.

The earth is warm because we receive radiation from the sun.  Much of this radiation reaches the atmosphere as short-wave radiation which passed through the atmosphere and reaches the ground. Some of the radiation is absorbed by the ground and re-emitted as ling-wave radiation which warms the atmosphere. They form a blanket around the earth, keeping in the long wave radiation and therefore keeping the air and the ground warmer than it would otherwise be. This effect is very similar to the way in which the glass in a greenhouse keeps the air and soil warm inside. There are methods of controlling greenhouse effect; by reducing the use of fossils and increasing afforestation, by banning the use of CFCs, by using unleaded petrol in vehicles and biogas for domestic purpose.