ATMOSPHERE AND CLIMATE CHANGE

After reading this, you should be able to:

1. describe the various regions of the atmosphere.

2. outline the effects of human activities on the , atmosphere.

3. describe the major pollutants of the atmosphere and their effects. '

4. explain Greenhouse effect on climate change.

5. explain the causes and effects of the depletion of the ozone layer.

6. explain the causes and effects of acid rain.











Regions of atmosphere is the thin layer of air surrounding the earth. The air consists of a physical or mechanical mixture of gases but not a chemical pomposition.

The atmosphere is divided into horizontal layers. These are the troposphere, stratosphere, mesosphere and thermosphere.

The troposphere is the lowest layer of the atmosphere. It extends from the earth’s surface to about 17km at the equator and 8km at the poles. The weather experienced on the earth’s surface is made in the troposphere. It is therefore referred to as the unstable zone. Within the troposphere, temperature normally falls with heights. The upper layer of the troposphere is called Tropopause.

The second layer of the atmosphere is the stratosphere and it extends from the tropopause to about 50km, where its upper layer: strapopause is found. Conditions in this layer are generally stable, especially at its upper limits. The stratosphere contains a lot of ozone. Inversion of temperature occurs in this layer. In other words, "temperatures rise with height. The presence of ozone causes the high temperature in this layer. This is because ozone absorbs great deals of the ultraviolet radiation from the sun, making the place hot.

The atmosphere extends upwards from the stratopause to about 80km. Its upper boundary is called mesopause. Within this layer, temperature decreases with height. This zone contains very little air, hence atmospheric pressure is low.

The thermoshere or innosphere lies above the mesosphere and extends up to 500-750km from the earth. In this layer, temperature inversion occurs again. The nitrogen and oxygen molecules and atoms within it absorb the ultraviolet radiation from the sun and therefore cause temperatures to rise. Its upper layer is thermopause. Just before the therrnopause, the thermosphere consists of higher gases such as hydrogen which are mostly ionized. These have little meteorological importance, except that they send radio waves to earth receiving Stations.






HUMAN ACTIVITIES AND THE R EFFECTS ON THE ATMOSPHERE

       Human kinds in the quest to improve upon life and make life more comfortable, embarked on a number of activities, some of which have devastating effects on the atmosphere.





ATMOSPHERE AND CLIMATE CHANGE

Some of these activities include;

1. All modes of transportation.

2. Energy production, refining and distribution.

3. Generation of electricity, for example, burning of coal, natural gas and diesel.

4. Use of refrigerants and coolants.

5. Smelting and other paper, chemical manufacturing and other heavy industries.

6. Mining of minerals or aggregates.

7. Application of pesticides for agriculture.

8. Waste incineration.

9. The use of various volatile chemicals; for example benzene.




The effects of these activities on the atmosphere are numerous; some of which are:

1. Release of carbon dioxide, carbon monoxide and other green house gases.

2. Depletion of the ozone layer.

3. Impairment of air quality.

4. SMO, including particulates and ground level ozone.

5. Effects on human and wildlife health; example, upper respiratory problems and higher rates of hospitalization.

6. Acidification of lakes and rivers (acid rain).

7. Deposition of air pollutions on land surface and water bodies.





SOURCES AND EFFFECTS OF ATMOSPHERIC POLLUTION

The major sources of atmospheric pollutants include the following:
1. Discharge of gases from factories.

2. Smoke from car exhausts, engines and other machines.

3. Smoke from domestic fires.

4. The discharge of chlorofluorocarbons (CFC’s) from aerosol sprays and some refrigerators.

5. Bush fires.

6. Smoke, heat and dust from volcanic eruptions.

7. Dust from desert areas and open cast mining

8. Burning of fuel like coal, oil and fuel wood. Methane from cattle manure and nuclear tests.




Some of the atmospheric pollutants have very serious consequences on the health and general well being of all living organisms. The effects could be direct. The effects of atmospheric pollutants have very senous consequences on the health and general well being of all living organisms. The etfects could be direct or indirect. The effects of atmospheric pollutants may include the following among others:

1.Global warming.
     Increased carbon dioxide, carbon monoxide and other green-house gases such as CFC‘s in the atmosphere traps the heat re-radiated by the earth, causing global warming.

2. Depletion of the ozone layer. The increased release of smoke, chlorofluorocarbons and methane depletes the ozone layer and thus the sun‘s energy may reach the ground direct. This can cause health hazards like skin cancer, respiratory problems and indigestion in humans. It also causes stunted growth in plants.

3. It causes rapid change in world climates. For instance, there will be a shift in wind belts and ocean currents. A shift in these phenomena would in turn cause a shift in rain belts. This could result in some places being too hot and others too cold. The use in temperatures could cause melting of permanent ice sheets at the poles. The result would be a rise in sea level and flooding of low-lying coastal areas and islands.

4. It can result in acid rain. The smoke and gases released into the atmosphere produce smog. When it rains, the rainwater dissolves some of the dangerous gasesin the smog to form acid solution called acid rain. Acid rain can destroy crops and other plants and can also cause a decline in soil fertility. This can lead to famine and other economic problems. Acid rain can also result in defacement of buildings and monuments, as well as corrode metals or structures such as bridges.

5. Atmospheric pollution leads to desertification and its soda-economic effects Desertifrcation could result from droughts and acid rain because both situations result in loss of plant cover. Crop failure can also be caused by drought and acid rain. The resultant effect is that famine is experienced in such regions together with other socio-economic problems which are directly or indirectly linked up with food shortages and famine.




GREEN HOUSE EFFECT; CAUSES AND EFFECTS

Green house effect is the process which cause: global temperatures to rise due to increasing amounts of carbon dioxide, carbon monoxide. methane chlorofluorocarbon (CFC’s) and nitrous oxide, in the atmosphere. These gases including ozone are known as greenhouse gases. They trap the heat re-emitted by the earth as a result of solar radiation, causing temperatures around the earth to rise. In this way they pollute the atmosphere. The effects of greenhouse gases are:

1. Global warming.

2. Depletion of the ozone layer.

3. Rapid change in world climates.

4. Falling of acid rain.

5. Droughts and desertification.

These factors have been discussed in detail in the last section on effects of atmospheric pollutants.









ASSESSMENT QUESTIONS

1. In which of the following layers of the atmosphere does temperature decrease with altitude?
a. Stratosphere
b. Exosphere
c. Troposphere
d. Ionosphere.

2. The boundaries of the horizontal layers of the atmosphere are determined by
a. air pressure.
b. temperature.
c. moisture content.
d. solar radiation.

3. The decrease in temperature with height is known as
a. temperature inversion.
b. radiation.
c. normal lapse rate.
d. convection.

4. Which of the following is likely to occur when there is concentration of carbon dioxide and sulphur oxides in the atmosphere?
a. Cyclone rain
b. Acid rain
c. Tidal rain
d. Hurricane

5. The lowest of the atmosphere is the a. exosphere.
b. thermosphere.
c. stratosphere.
d. troposphere.

6. In which of the layer of the earth's atmosphere is the ozone layer at its maximum?
a. The Troposphere
b. The Mesosphere
c. The Thermosphere
d. The Stratosphere.

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