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Date: Sun, 25 Apr 2010 Time: 10:07 PM -
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The atmosphere consists of a number of gases, the most important of which from the point of view of life on Earth is oxygen. It is a by-product of plant metabolism. It is essential to the metabolism of animals, and it also takes part in an important reaction in the stratosphere.( http://www.imitatewatch.com/GoodsBrand/Replica-Audemars-Piguet-Watches-6.html)
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The oxygen molecule consists of two atoms of oxygen-written as O2. In the stratosphere the ultraviolet rays of the sun can break the molecule down into individual atoms—O and O. These atoms are unstable and can attach themselves to other oxygen molecules to form molecules of ozone oxygen with three atoms of oxygen—O3. Under the influence of radiation from another part of the ultraviolet spectrum the molecules of, ozone can break down and unite with more free oxygen atoms to form oxygen molecules again—O3 unites with O to produce O2 and O2.
As a result there is a layer in the atmosphere where ozone is continually produced and destroyed. This o-zone layer lies between 15 and 50 km above the ground—with the greatest concentration at about 23km—and is estimated to contain about 5 billion tones of ozone at one time. All this activity absorbs the energy of the ultraviolet light and prevents it from reaching the ground, which is a good thing as certain wavebands of ultraviolet light can cause cancers, cataracts, and decreases in crop yields.
The presence of certain other molecules, particularly of chlorine, influences the speed of these reactions— usually increasing the speed of the breakdown of the ozone. This is very noticeable in springtime in the Antarctic when chorine from pollutants in released from the icy winter clouds. The ozone concentration is reduced here, and the still conditions cannot bring it in from elsewhere, resulting in the so-called ozone hole. It is believed that much of the chlorine responsible comes from industrial gases such as CFCs, as well as from natural sources such as volcanoes. This is becoming a worldwide problem as a thinning of the ozone layer over Europe was detected early in 1993.
Using Land Wisely,A very important world problem — in fact, I am inclined to say it is the most important of all the great world problems which face us at the present time — is the rapidly increasing pressure of population on land and on land resources.( http://www.luv-replica.com/GoodsBrand/Rolex_Ladys_Replica_Watches-23.html)
It is not so much the actual population of the world but its rate of increase which is important. It works out to be about 1 -6 percent per annum net increase. In terms of numbers this means something like forty to fifty-five million additional people every year. Canada has a population of twenty million— rather less than six months' climb in world population. Take Australia. There are ten million people in Australia. So, it takes the world less than three months to add to itself a population which peoples that vast country. Let us take our own crowded country— England and Wales, forty-five to fifty million people — just about a year's supply.
Now turn to our own country. Audemars Piguet Replica Watches Including land of all sorts, there is just over one acre per head in the United Kingdom of Great Britain and Northern Ireland. That is why we have to be so very careful with it Replica Rolex Ladys Watches. How much do we actually use?
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