What are the main components of environment?

Aug 26, 2022, 16:45 IST

Components of Environment:

Environment comprises of four major components:

1) Atmosphere 2) Hydrosphere 3) Lithosphere 4) Biosphere

Atmosphere:

It is a protective cover of gases which is surrounding the earth. It has no well defined upper limits and gradually merges with the outer space.

Constituents of atmosphere are gases, water vapour and aerosols. Pure dry air on an average constitutes 78% nitrogen and 21% oxygen by volume. Remaining 1% accounts for other gases.

(Table for atmospheric composition)

The main constituents which are of great importance for the earth’s climatic conditions are dust particles, carbon dioxide and ozone. The total mass of the atmosphere is about 5 x 10¹⁵ tonnes. The air at the surface of earth is compressed by weight of the air above it. Hence, density as well as pressure of the atmosphere decrease as we go higher above the earth surface.

Of the total mass of atmosphere about 99% is within a height of 30km from the earth’s surface. 

On the basis of variation in temperature with increasing altitude, the atmosphere has been divided into the five distinct zones. These zones are troposphere, stratosphere, mesosphere, ionosphere and exosphere.

i) Troposphere: It is the domain of all living organism including plants and animals. It extends roughly to a height of 11km from the earth surface. This is the thinnest layer of the atmosphere, yet it contains about 80% of the total mass of air and all the water vapours and dust particles are concentrated in this zone. This region is greatly affected by air pollution. The temperature of this region decreases with altitude roughly at a rate of 6.4/km and is minimum at about 11 km. The temperature drops upto – 55⁰C at the height of about 11km. The concentration of the water vapours varies from place to place and from time to time at the same place. As the water vapours are carried upward, they cool, condense into cloud particles and return to the earth’s surface by rain (precipitation). Another important constituent of troposphere is the aerosols or suspended particles. Most of the suspended particles act as nuclei around which water vapours condense to form clouds. Smog is also caused by the presence of suspended particles in the atmosphere.

Physics Wallah Chemistry Doubts page consist of more questions for reference. 

ii) Stratosphere: It extends from 11 to 50 km. This zone is characterised by the absence of changing weather pattern. In the stratosphere temperature begins to increase. The point at which temperature inversion takes place is called tropopause. The ozone present in the stratosphere absorbs the harmful ultraviolet radiation coming from the sun. The rise in temperature is due to absorption of ultraviolet rays which is converted into heat. In the stratosphere, temperature ceases to fall and remains constant upto the height of 20km. Afterwards it gradually increases upto the height of 50km where it reaches to about – 2⁰ Chemical species present in the stratosphere are N₂, O₂ and O₃. The formation and destruction of ozone by the natural process is a dynamic equilibrium between O₂ and O₃. This equilibrium maintains a concentration of ozone in the stratosphere. Due to the presence of ozone layer, this region is also called ozonosphere. Concentration of ozone in stratosphere ranges between 1 to 5 ppm by volume. Startosphere is comparatively calm and is much less dense than the troposphere. If the pollutants reach the stratosphere, they will stay there for quite a long time and hence will become long term health hazard.

iii) Mesosphere: Above the stratosphere is mesosphere. It extends from 50 to 85km. It contains low concentration of oxygen and nitrogen and posses little capacity to absorb solar radiation. Hence, temperature again decreases with height to an exceedingly low value of about – 100⁰C. The region of minimum temperature is the limit of mesosphere and is known as the mesopause.

What are the main components of environment? pdf