All living things on the earth are associated with air, water and land. Air, water and land are called the earth’s atmosphere, hydrosphere and lithosphere, respectively.
Moreover, different living things occupy these three spheres of the earth.
These living things and therefore the parts of the lithosphere,
hydrosphere and atmosphere which they occupy are
together called the biosphere.
These spheres have formed on the earth naturally. The atmosphere is that the layer of air that surrounds
the earth. The surface of the earth comprises water and land, that is, the hydrosphere and lithosphere. Of
these, the hydrosphere occupies a much larger part than the lithosphere.We also look upon these natural components in solid, liquid and gaseous form as resources. In other words, we use them to fulfil our requirements. Let us
now study all these three components in detail.
The air in the atmosphere around the earth contains nitrogen, oxygen, carbon dioxide,
six inert gases, nitrogen dioxide, sulphur dioxide, water vapour and dust particles. The
troposphere contains about 80% of the total mass of gases in the air, while this proportion
is about 19% in the stratosphere. Further, in the mesosphere and ionosphere, the proportion
of the mass of gases goes on decreasing. Gases are not found in the exosphere and beyond.
Some Uses of Gases :
1] Nitrogen – Helps living things to build the necessary proteins. It is useful in the production of ammonia and in airtight packaging of foodstuffs.
21] Oxygen – Necessary for respiration in living things and for combustion.
•3] Carbon dioxide – Plants use CO2 for producing their food. Used in fire extinguishers.4]
4] Argon – Used in electric bulbs.
5] Helium – Used for obtaining low temperature and also for generating lift in airships.
6] Neon – Used in decorative lights and for street lighting.
7] Krypton – Used in fluorescent tubes.
8] Xenon – Used in flash photography
Air Pollution :
This smoke directly mixes with the atmosphere, disturbing the balance between the constituents of air. This is called
Harmful substances released in air through combustion of fuels
Ozone layer – the protective shell. There is a layer of ozone (O3) gas in the lower part of stratosphere. Ozone gas is
not directly useful for the survival of living things, yet it is very important for living things to have this layer of ozone at a high altitude around the earth. The ultra violet rays coming from the sun are very harmful
for living things. The ozone gas absorbs these rays. As a result, life on earth is protected. The ozone layer is destroyed if chemical gases like carbon tetrachloride or the chlorofluorocarbons used in air conditioners and refrigerators mix with the air.The 16th of September is celebrated as ‘Ozone Protection Day’ all over the world to make everyone aware of the
importance of ozone.