The Ozone LayerIn environmental science the green house effect is a common term for therole water vapor; carbon dioxide and ozone play in keeping the earth’s surfacewarmer than it would normally be. The atmosphere is primarily transparent toinfrared radiation from the sun, which is mostly absorbed by the earth’s surface. The earth being much cooler than the sun, remits radiation most strongly atinfrared wavelengths. Water vapor, carbon dioxide and ozone then absorb much ofthis radiation and remit a large proportion back towards the earth.
Theatmosphere thus acts as a kind of blanket: without its presents the earth’saverage ground temperature of 15 degrees Celsius would fall to -28 degreesCelsius. The termed greenhouse effect implies that a comparable effect keepsthe interior of the green house warm. Actually, the man role of the glass in agreen house is to prevent convection currents from mixing cooler air outsidewith the warmer air inside. Although water is the most important factor in the greenhouse effect, isa major reason why human regions experience less cooling at night than do dryregions. Changes in both water and carbon dioxide play an important role inclimate changes.
For this reason many scientist have expressed concerns overthe global increase of carbon dioxide in resent decades, largely as a result ofthe burring of fossil fuels. In many other factors of the earth’s presentclimate remain more or less constant, the carbon dioxide increase should raisethe average temperature at the earth’s surface. Because warm air can containwarm water before reaching saturation than cooler air can, the amount of waterwould probably increase as the atmosphere got warmer . This process could go onforever. Although this considered unlikely many negative feed backs could as sooccur, such as increase in cloud cover or increase carbon dioxide absorptionby the oceans, the results of even a limited rise in average surface temperatureremains sufficiently dramatic to justify concern.
In October 1983 the US Environmental Protection Agency released a reportthat projected the irreversible onset of the greenhouse effect by the 1990’s. Shortly there after the National Academy of Sciences issued its own report, inwhich the matter of irreversibility remain more in question. Both reports,however, strongly indicated the need for measures to check the rise in carbondioxide. No matter what term you use global warming or greenhouse effect, theyboth play a major role in the earth’s climate. Climate researchers areattempting to predict, based on ocean and air circulation, how great an increasethere will be. If global warming continues then the polar ice caps will melt andmost of the earth will be flooded and a lot of lives will be lost.
The Ozone is located in the stratosphere, approximately 10 km – 50 kmabove the earth. The density of ozone gas at zero degrees Celsius is 1 ATM. The Ozone is relatively unstable form of molecular oxygen containing threeoxygen atoms (O ). Radiation from the sun continuously bombards the Earth’satmosphere, causing molecules to break apart into component elements that forminto new chemical compounds. Ozone is produced when upper-atmosphere oxygenmolecules (O ) are broken apart by ultra-violet light. Most of the freed oxygenatoms immediately bond with nearby oxygen molecules to form ozone (O + O =O ).
The only method used to make commercially is to pass gaseous oxygen or airthrough a high voltage alternating-current electric discharge called a silentelectric discharge. Ozone near the earth’s surface is generally regarded to asa bad . It is created from industrial, transportation, and some naturalsources. It is the most noxious component of smog.
All high concentration, 0is known to reduce human lung capacity, as well as damage the cells of manyplants, animals, and other organisms. For these reasons, ozone is treated asand air pollutant in most industrial countries. Furthermore, O in the uppertroposphere is a powerful greenhouse gas and is believed to play a role inglobal warming. On the other hand, ozone in the stratosphere is highly valued. Itserves as a protective radiation shield that interprets solar ultraviolet lightharmful to living things.
Ultraviolet light splits the relatively unstable Omolecules into O and atomic O. Most of the time, the O atom created by Ozonebreakup recombines with one of the plentiful O molecules to re-form O . ThisOzone-creation process is constantly at work producing more ozone. Scientistcan’t predict with certainly the consequences for life on the earth if thestratosphere ozone layer weakens. In general, biologists and healthprofessionals recognize that life on earth enveloped under the protection of anozone layer thick enough to remove much of the UV-B solar radiation known todamage cellular organisms.
Accordingly, various organisms–including humans–may have difficult adjusting to the higher UV-B levels resulting from a thinnerozone Layer. Medical studies have quantified some of the expected effects ofincreased UV-B levels, based on real-life information form people exposed togreater than average UV-B levels–populations living at high altitudes and inthe tropics, where the average ozone layer is thinner and the sunlight moredirect. The most serious medical effects include increased incidence ofcataracts and skin cancer, as well as evidence of weakened immune-systemresponse. Ecological research indicated that some crop yields will decrease anddisruption in marine food chains may occur. A weakened ozone layer may also case climatological effects.
Thestratosphere warms with altitude because the splitting of stratospheric ozone iscaused by ultraviolet photons, which contain much more energy than that requiredto break the O-O bond. This extra energy is converted to heat. Lessstratospheric ozone means less local heating, but it also means that more UVlight is transmitted to heat the lower atmosphere and the earth’s surface. Ozone can be destroyed by chemicals that react directly with it, or bythose that react with the oxygen atom temporarily freed whenever an o moleculebreaks apart. However, since ozone concentrations are higher than those of mostreactive chemicals in the stratosphere, the only ozone destroyers of concern arethose that can participate in a “catalytic cycle” that is, where one tracecatalytic chemical can be responsible for destroying terns or even hundreds ofthousands of ozone molecules. In the last few years, various human activities have released ozone -destroying chemicals into the atmosphere.
Of Particular importance are halogenatoms — chlorine and bromide. Chemicals release into the ozone by industrialparticles include chlorocarbon compounds (such as CCL and CHI CL ),chloroflucarbon compounds CFCs and halon compounds. Chlorocarcon compounds are used primarily as industrial solvents,degreasing compounds, and CFC precursors. The CFCs are used as working fluidsin refrigeration and air conditioning units.
Aerosol propellant agents. TheHalons are used as fire suppressants. Once in the stratosphere, all thesechlorine and bromine containing compounds are broken apart by solar ultravioletradiation, releasing their Cl or Br atoms. These atoms start the process ofOzone destruction.
Each Chlorine of Bromine atom that starts the destructioncycle can destroy 100,000 ozone molecules. There are on the other hand naturalozone depletes such as volcanic eruptions. A hole in the Ozone has emerged because of all of the depletion. Starting in the spring of 1980, a massive 8. 2 square mile ozone hole accountingfor one quarter to one half the appeared over the continent of Antarctica. Forthe past 16 years the hole has grown larger.
There was a theory that predictedthat the most severe O loss would occur relatively high in the stratosphereabove 30 km). It was called the Roland/Molina theory. In fact the largestdepletion over Antarctica occurred in the middle range between 13 and 21 km. Atmospheric chlorine and bromine levels are expected to peak around 1998. There are currently steps being made to protect the ozone.
One suchstep is the 1987 Montreal Protocol on substances that harmed the ozone. 37nations signed the bill, it read that the signing nations cut down on the use ofchlorofluorocarbons and to completely stop CFC emissions by the year 2000. Ingeneral people are waking up to this serious problem; as well they should. Themore ozone that is destroyed the more UVA rays and UVB rays that reach the earth.
It is hypothesized that by the year 2086 if depletion continues at the currentrate that no living organism will be able to survive on on earth unless theyare underwater. Ozone is debatibly the most important thin known man. The survival ofthe human race is really dependent upon the ozone layer. If we keep using thesedangerous chemicals, such as CFC, found in arisol cans, we could ultimatlydestroy the ozone layer. If we destroy the ozone layer then we are reallykillling ourselves.
If the ozone layer is destroyed then powerful ultriviolentrays will penitrate the earth and everyone would get skin cancer and eventuallydie. I hope organizations will continue to work to prevent the distruction ofozone because I would like to see man survive for a while.
