According to meteorological
researches the atmosphere is divided into five thermal zones- the troposphere-
10 km above the sea level; stratosphere 10 to 40 km; mesosphere 40 to 70 km;
ionosphere 70 to 400 km; and exosphere above 400 km.
Ozone Depletion - Effects of CFCs
Stratosphere contains negligible amount of water vapor
and dust. Strong jet streams blow in this layer which affects the weather of
the earth. For convenience this layer may be divided into two parts called
stratospheric layer and ozonosphere. Stratospheric layer exists only up to 25
km height and its temperature remains almost constant. Ozonosphere contains
ozone and it exists between 25 km to 40 km. ozone is essential to life on earth
because it acts as a safety shield for the earth. Ozone forms a hot layer by
absorbing about 90% of short ultraviolet rays of sun which are harmful for the life
on earth.
Ozone Depletion
In nature ozone is formed from oxygen by ultraviolet radiations
of the sun. These two gases remain in equilibrium or balanced condition. But
recently oxygen-ozone balance has been upset by the excessive presence of
chemical pollutants in the atmosphere. Scientists believe that ozone layer is
becoming this over Antarctica.
Man made chemicals especially chlorofluorocarbons adversely
affect the ozonosphere. Freon gas is also a chlorofluorocarbon which is used in
refrigerators. These chemicals are also used in air-conditions, aerosol spray
and plastic foams. Free chlorine atoms of these compounds have disturbed the
ozone equilibrium. Ozone depletion will cause dreadful disease like skin cancer
and skin allergies. It may also have hazardous effect on plants and other
animals. To save our earth we have to discover substitutes for
chlorofluorocarbons which do not cause ozone depletion in atmosphere.
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