Haritima : The Environmental Society Of Hansraj College



A molecule containing three atoms of oxygen is named ozone.

It is very rare in our atmosphere, averaging about three molecule of ozone for every 10 million air molecules.

The ozone layer is mainly found in two regions of the earth’s atmosphere.

Most ozone (about 90%) resides in a layer that begins between 6 and 10 miles (10 and 17 kms). This region of atmosphere is called Stratosphere and ozone here is commonly known as Ozone Layer.

The ozone layer is mainly found within the lower portion of stratosphere. It contains high concentrations of (O3) relative to other parts of the atmosphere.


  • O3 layer in stratosphere absorbs some of the radiation from the sun, preventing it from reaching the earth’s surface.
  • It absorbs the portion of UV light called UVB. It prevents humans, crops and marine animals from many harmful effects.
  • Basically O3 layer act as shield that absorbs 97 to 99% of the sun’s MF UV light, which otherwise would potentially damage exposed life forms near the surface.
  • It control the temperature of our earth, thus make suitable for all living organisms to survive.

Moreover, due to its extra heat ozonosphere also acts as a blanket that reduces the cooling rate of the earth and thus adds to the effect of water vapour.


  1. Growth Rate: The Annual average rate of change of population size, for a given country or territory or for a geographical area, during a specific time period is known as growth rate.
  2. Total Fertility Rate: It is defined as the average of children that would be born to a woman in her lifetime if the age specific birth rates remain constant.
    • It varies from 9 in developed nations to 4.7 in developing nations.


  1. Infant Mortality Rate: It is calculated by dividing the number of deaths of children under age of one by the number of live births in the same year and multiplying by 1000, and is inferred as probability of a child born in a specific year or period, dying before reaching the age of one.
  3. Age Structure: Age Structure of population of a nation can be represented by age pyramids, based upon belonging to different age classes like pre-reproductive (0-14 years), reproductive (15-44 years) and post reproductive (45 years and above).


  • Pyramid shaped: More young, less old population thus, making a broad base.
    • Examples are India, Bangladesh, and Nigeria.
    • Individuals in large numbers at a very young age will soon enter into reproductive age, thus causing an increase in population.

And less number of people in old age indicates less population due to death.

error: Content is protected !!