When the Earth was formed, many layers of gases came up and covered the Earth’s surface. Similarly, the ozone layer, also known as ozone shield, was formed in the stratosphere region of atmosphere. Stratosphere extends from 15 to 60 km above the earth’s surface. This layer absorbs ultraviolet rays given out by the sun. It contains high content of ozone gas i.e. O3 gas. This layer is mostly found in the lower layer of the stratosphere. The thickness of this layer varies according to the season and geographic conditions. This gas is formed naturally. Its chemical formula is O3. In the presence of halogens, the oxygen in the atmosphere gets converted into ozone molecules. The Ozone layer protects the living beings on earth to sustain life. A diminishing zone will allow the harmful ultra violet rays to reach the earth and cause irreplaceable damage.
The Ozone layer was first discovered by French physicists Henri Buisson and Charles Fabry. They made an in-depth study of this layer and came out with many results. They also made an instrument called the spectrophotometer which was used extensively to measure the density of the ozone layer and its distance from the ground level. In the middle of the 20th century, Dobson came up with an instrument, which later came to be known as Dobson meter. This was used to measure the ozone in the stratosphere by setting up many ozone monitoring stations. These stations operate there till date and are used to send the latest updates from the ozone layer. This instrument was used to measure the amount of ozone overhead in the atmosphere. Sydney Chapman, a physicist of British origin, came up with this conclusion that certain photochemical mechanisms gave rise to the ozone layer. He said that oxygen molecules were bombarded by ultraviolet light. This process broke down the oxygen molecule into separate oxygen atoms. This process continues for a long time and this process is called as ozone-oxygen cycle. The Ozone layer is scattered in the lower part of stratosphere. If we try to compress all the ozone we have in the atmosphere, then it will amount to only 3 millimetres of thickness in the air at sea level.
The Ozone layer is not equally divided across all the areas on the earth. You will find that there is a higher concentration of ozone layer near the North Pole than the South Pole. As we come towards the South Pole, the intensity of ozone gas goes on decreasing. There are also variations according to the seasons. For example, you will find a thicker ozone layer in the season of spring but when autumn comes, this later reduces its width. Other factors affecting the width and density of ozone layer are latitude and seasonal complications. Various patterns in atmosphere are also a major reason. The behaviour of ozone gas is very unpredictable. When winters come, this layer actually increases its width. In the altitudes and the tropical areas, the content of ozone is comparatively higher. In lower altitudes, the concentration of ozone gas is comparatively less. This variation is because of the slow circulation which lifts up the ozone air away from the troposphere region, into the stratosphere area. Now, when the sun overheats the oxygen molecules, ozone gas is produced which forms up the ozone layer. One interesting fact about ozone layer is that although it protects the earth from ultra violet radiation, it is made with the help of UV rays given out by the sun.
Every minute, we can see three molecules of oxygen join together to form ozone. Hence, you are saved from the harmful effects of the sun rays. This layer is very important for life on earth. This is because it prevents the UV radiations from coming to the earth. It filters all the unwanted radiations. If there is no ozone layer, then the UV rays will directly reach the earth’s surface. If people are continuously exposed to these rays then they can suffer from skin cancer. Cataract and weak immune systems are other diseases caused by a depleted ozone layer. This layer also balances the polluting gases from disturbing the composition of gas and other particles.
Lately, the stratosphere layer and the ozone layer are being destroyed by various chemical reactions taking place on Earth because of pollution and other sources. Chemicals containing chlorine and bromine are the main factors which are destroying the layers there. These chemicals are also called as an ozone depleting substances i.e. ODS. Actually they are very stable chemicals in the environment. This is why they go up in the air, beyond the atmosphere and into the ozone layer. As they rise up, they are broken into molecules by the UV rays. As the result of this reaction, they form chlorine and bromine. These two are the major chemicals which disrupt the ozone layer. Worst part is that these ODS can live in the atmosphere for a long time. Some of them can last for more than 80 years. Thus they add a lot to the depletion of ozone layer. These ODS are so slow that they can take up to three to four years to reach the stratosphere layer.
Recently new gases like Hydro fluorocarbons i.e. HFCs and others have been detected by scientists. These gases are majorly emitted by cooling appliances like refrigerators and air-conditioners. HCFs are not responsible for the depletion of ozone layer, but they are more of the gases which contribute to the globally changing climate. CFCs are yet other gases which highly damage the ozone layer. This gas is used to maintain the cool temperature in freezers, air conditioners, refrigerators and car manufacturing processes. It is also found in hospital sterility as well as dry-cleaning agents. Halons also destroy the natural composition of ozone layer. This gas is used in fire extinguishers and other processes. They are far more risky and harmful than CFCs. Other gases like Methyl Chloroform, Carbon Tetrachloride and others highly damage the ozone layer. Methyl bromide is used in soil treatment plants, pest control, and market gardening. In Ireland, the use of this chemical is illegal and it is banned from being used any more. This chemical is 40 times more destructive than the chlorine atoms. Every year, oceans and volcanoes give out large amounts of chlorine. This chlorine dissolves in water and goes up in the form of vaporization. Clouds having a high content of chlorine are formed. When it rains, this chlorinated water falls and disturbs the level of ozone layer. CFCs, unlike chlorine, do not dissolve in the atmosphere. Such gases not only damage the health of the population on earth, they also cause huge damage to the growth of crops and pulse. The marine food chain is damaged considerably. This leads to a huge gap between the supply and demand of marine products.
Every year, September 16 is celebrated as International Ozone day. This is to let people know the importance of Ozone layer in the atmosphere. High amount of ozone depletion was observed in 1980s around the Antarctic regions. There has been made a pact named as Montreal Protocol. Today, more than 190 countries are a part of this pact and have signed the Montreal Protocol deal. It is one of the most successful pacts made with regard to environment concern. It is a commitment made by the countries to eliminate the frequent production of harmful gases which will damage the ozone layer. In 2012, Montreal Protocol marked its 25th anniversary. A short video was prepared to throw light on issues related to the ozone layer. In the year 1978, the use of CFC was completely stopped in the U.S. Efforts are being made to substitute chemicals containing CFCs with other less harmful chemicals. From the year 1996, only recycled and eco-friendly CFCs are used in the US and other developed countries.
The ozone which has been depleted cannot be recovered in any way now. The destroyed ozone has caused much loss to our mother earth. But preventing further destruction of this useful layer is very essential. If we put a limit on the use of products which release gases causing ozone depletion, then we can restore the ozone level to its required limit. In this line, we should be able to bring our ozone to its normal level by 2050. It is very important to keep a watch on pollution and other harmful agents to prevent the loss of mankind from harmful UV rays.
The ozone layer is what saves the Earth from the harmful UV radiations of the sun. It is important to understand more about what is the ozone layer.