Which gas is the third most abundant in the Earth's atmosphere?

The composition of the atmosphere comprises of 4 major gases with the others present in very small amounts.

Argon is the 3rd most abundant gas (0.934%) in the atmosphere. It is a colourless, odourless, and tasteless inert gas of Group 18 (noble gases) of the periodic table. It was isolated in 1894 from air by the British scientists Lord Rayleigh and Sir William Ramsay.

If the oxygen concentration is less than 19.5 % in the atmosphere, various physiological changes can take place in all the life forms on Earth. An atmospheric condition with oxygen amount below 16% is life threatening to all the organisms.

Atmospheric air consists of certain elements in a specific ratio. According to NASA (National Aeronautics and Space Administration), 99.998% of the Earth’s atmosphere is made up of these 4 compounds.

These major components are nitrogen (78.084%), oxygen (20.947%), argon (0.934%), and carbon dioxide (0.033%). Another major constituent is water vapor, which is not included in studying the dry composition of air. Air composition without water vapor is called dry air. The percentage of water vapor may range from 1 – 5%.

The components present in the air other than the above-mentioned 5 main ones are referred to as trace elements, as their quantity is small. The atmospheric air composition remains nearly unchanged up to an altitude of 10 metres. Any major alteration in the percentage of different elements is associated with changes in the global climate.