Question

How is air useful to us?

Answer 1

We can define air as an invisible mixture of gases and dust particles that constitutes the majority of our atmosphere and surrounds the earth. Besides its life giving property, think in terms of how we are able to light a fire when we feel cold, or how we do not get hit by meteors though there are so many flying through the atmosphere, or how windmills produce energy or how we are able to hear sounds and how we are able to have a sustainable habitat for living. The constituents of air have something to do with all of these processes, and many more!

Complete answer:
We know that air contains a mixture of gases and each constituent plays a vital role in the functioning of all living beings and all ecosystems. Besides sustaining life on earth and maintaining the well being of all living beings via plants using atmospheric carbon dioxide to release oxygen through photosynthesis, air contributes to other important processes and has a versatile range of applications. Let us look at few as examples:
1.Combustion:
The oxygen present in the air supports burning or combustion and helps in generating heat and in the burning of fossil fuels which basically powers industries and automobiles.
2.Source of Energy:
Moving air has kinetic energy. Windmills and wind turbines harness the kinetic energy of motive air to convert into electrical energy. This is a pollution-free production of electrical energy.
3.Heat Trap and Temperature Control:
The air in the atmosphere traps the heat energy incident from the Sun, keeping the earth warm and habitable. In the lower layers of the atmosphere, there is always a constant circulation between hot air and cold air via convective processes which facilitates the smooth running of the water cycle by holding water vapour.
4.Protection:
The air in the atmosphere (like the stratospheric ozone layer) acts as a deterrent against harmful space radiation impinging towards the Earth, and it is also responsible for burning up large meteors which would otherwise impact the surface of the earth, causing disasters.
5.Propagation of sound:
Air acts as a material medium through which the compressions and rarefactions of the sound wave are propagated through. Without air, there would be no medium particles to which sound waves could transfer their vibrations to and propagate. Thus, we are able to hear things because of air.
6.Atmospheric Pressure:
The atmospheric pressure exerted by air is responsible for maintaining our blood pressure, in the absence of which we would suffocate from all the blood splurging out to the no pressure region. This is also why astronauts in space wear spacesuits and we don’t have to. The air pressure also keeps the necessary gas molecules dissolved in water, ensuring the survival of the aquatic habitat.

Note:
Note that the heat trapping capability of air is not necessarily good. This is because, as a consequence, the air in the atmosphere holds in some greenhouse gases (like carbon dioxide, methane, water vapour and nitrous oxide) that retain most of the heat coming from the Sun and contribute to the abnormal warming of the planet. However, humans are a greater contributing factor to global warming which is catalysed by the emission of pollutants like CFCs (chlorofluorocarbons).