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The atmosphere is important for us in many ways , it helps in creating the necessary pressure around the earth which leads to water and its existence in liquid form. Secondly , it also absorbs the harmful UV rays of the sun which can cause various diseases. The presence of gases in the atmosphere also regulates the earth’s temperature.
History of air.
The first atmosphere had hydrogen and its hydrides like water vapour, methane and ammonia as the composition of air.
After the eruption of volcanoes and the crashing of asteroids a new atmosphere was formed with a new composition of air. This atmosphere had nitrogen, carbon dioxide and many rare gases. Sediments dating back to 3.8 billion years state that carbon dioxide was mixed with water and it reacts with other metals and for me crystal formations of carbonates.
The second atmosphere saw its majority portion being captured by nitrogen . It was a stable atmospheric condition back then. Apart from the ice Age 2.4 billion years ago the earth had a warm climatic condition. After the ice Age cyanobacteria were seen which led to the Great Oxygenation event. Evidence of the process is found in fossils.
The third atmosphere saw the great oxygenation event which took place 2.4 billion years ago. Before this there was no presence of oxygen in the composition of air. This oxygen later became very important for life and other metallic oxidation processes. Considerable amounts of changes in the oxygen levels have been observed with fluctuations between 30% back in the day but now it is 20% . However the presence of oxygen enhances human lives.
Composition of air
The air comprises of the following :-
About 78 % is nitrogen .
20% of the air is filled with oxygen.
0.97% are inert gases.
Carbon dioxide and other gases cover up 0.03% of the atmosphere .
The remaining 1% has water vapour as a component.
Pie Chart description of the composition of air shows the various gases which are present in the air along with their quantities of existence.
Short notes on the components of the air
Nitrogen – This is gas found in most abundance in the air. It is a gas discovered back in 1772 by Daniel Rutherford. It is depicted by N and has an atomic number of 7.
Oxygen – It is the second most abundant gas in the air. Its uses are not unknown as it is the basic need for living organisms and animals for respiration . Oxygen is denoted as O and has the atomic number of 8. Joseph Priestley discovered oxygen in 1774.
Rare gases – These gases are also known as inert gases. These gases do not react with any other substance at given circumstances and are hence called inert gases .
Carbon Dioxide – It is found in the atmosphere with 0.03% of the total air. Carbon dioxide is used by plants for photosynthesis and producing oxygen . Carbon dioxide is also used in making carbonated drinks too .
Other gases and water vapour – Water vapour is the gaseous form of water and also has the same formula as H2O. Along with a few more gases and itself, they contain 1 % of the composition of air.
Conclusion
The composition of the air determines a lot of things for the living and non living beings. The composition of air is the determining factor of the earth’s temperature. The gases in the air have their respective uses too . One of the most important gases in the air is the ozone, as it forms a layer around the earth’s atmosphere and prevent s the harmful UV rays of the sun from protruding inside it. Gases like carbon dioxide and CFCs are present in lesser quantities but they cause higher temperatures of the atmosphere, known as global warming.
