JSS3 First Term Basic Science Lesson Note – Depletion of Ozone Layer and Its Effects

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 WEEK FIVE

DEPLETION OF OZONE LAYER AND ITS EFFECTS

Description of the Ozone Layer and its Location in the Atmosphere

The earth’s atmosphere is divided into three layers namely: troposphere, stratosphere and ionosphere. Ionosphere is further divided into mesosphere and thermosphere.

The ozone layer is located in the stratosphere. Ozone forms a layer of the upper atmosphere, where it acts as a shield that prevents most of the ultraviolet radiation in sunlight from reaching earth’s surface. In recent years, reports from atmosphere research satellites have shown that the ozone layer is vanishing or depleting than it can be regenerated naturally. This has cause a lot of concern among those who know the effects of what is happening to ozone layer.

 IMPORTANCE OF THE OZONE LAYER

The ozone layer forms a protective shield against some kinds of radiation produced by the sun.

The radiation is the ultraviolet rays emitted by the sun. The rays pass through the layers of the atmosphere and they are absorbed by the ozone layer, thereby protecting human beings and other living organisms from harmful ultraviolet rays.

CAUSES OF OZONE LAYER DEPLETION

The major cause of ozone layer depletion is the accumulation of a chemical called Chlorofluorocarbon (CFC ) which is a chemical used for refrigeration, as propellant in aerosol and for other manufacturing processes. The ways in which CFC destroys the ozone layer are as follows:

1. Chlorine from CFC reacts with ozone, chlorine monoxide and oxygen are formed
2. Two molecules of chlorine monoxide react to form chlorine peroxide
3. Sunlight causes chlorine peroxide to break it down into oxygen and free chlorine atoms
4. The chlorine atoms can then bring the cycle again and again

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