Ozone Layer Depletion

Topics: Ozone depletion, Ozone layer, Ultraviolet Pages: 4 (943 words) Published: February 5, 2014
The upper layer of the atmosphere surrounded by ozone (15 to 30 Kms) is known as ozonosphere. Ozone layer is a protective stratospheric layer, also known as ozone umbrella.

Ozone concentration differs by about 10 ppm in stratosphere compared to 0.05 ppm in troposphere. It acts as a protective shield for the man, animals and plants by filtering out the lethal ultraviolet rays from reaching the earth’s surface.

If the ozone layer is not there, the harmful ultraviolet rays will reach to the lower atmosphere and its temperature will rise to that extent that the biological furnace of the biosphere will turn into a blast furnace.

Formation of Ozone

The atmospheric oxygen absorbs UV radiation in the lower mesosphere at < 240nm and Photo dissociates into two oxygen atoms.

One of these oxygen atoms combines with 02 of upper stratosphere forming 03. Ozone is also capable of absorbing short wavelength UV radiations releasing oxygen atom.

Reactions: 02 + hv {X < 240 nm) O + 02 + M 03 + hv (A, > 230-320 nm) O* + o,

Ozone Hole or Ozone Layer Depletion

The latest satellite measurement indicates an ozone loss at the rate of 8% just above the South Pole, at the centre of the ozone hole, 5% of the protective gas is depleting each day.

In 1980, a hole in the ozone umbrella was found out by a scientist named Chubachi Shigerui of Meteorological Research Institute of Japan. By the year 1985, this hole reached to the size of the American continent.

Factors Affecting 03 Layer Depletion

The main cause of 03 layer depletion is the presence of chlorine containing gases (primarily CFCS and related hydrocarbons).

Due to the presence of UV light, these gases dissociate and release chlorine atom, which then leads to O3 destruction. The chlorine ion catalyzing O3 depletion can take place in the gaseous phase, but it is dramatically enhanced in the presence of polar stratospheric clouds.

During extreme cold in winters polar stratospheric clouds (Pscs) are...
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