File Name: ozone layer and its depletion .zip
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In the stratosphere the temperature of the atmosphere rises with increasing height, a phenomenon created by the absorption of solar radiation by the ozone layer. In the midlatitudes the peak concentrations of ozone occur at altitudes from 20 to 25 km about 12 to 16 miles. Peak concentrations are found at altitudes from 26 to 28 km about 16 to 17 miles in the tropics and from about 12 to 20 km about 7 to 12 miles toward the poles.
The lower height of the peak-concentration region in the high latitudes largely results from poleward and downward atmospheric transport processes that occur in the middle and high latitudes and the reduced height of the tropopause the transition region between the troposphere and stratosphere.
Near-surface ozone often results from interactions between certain pollutants such as nitrogen oxides and volatile organic compounds , strong sunlight , and hot weather.
It is one of the primary ingredients in photochemical smog , a phenomenon that plagues many urban and suburban areas around the world, especially during the summer months. The production of ozone in the stratosphere results primarily from the breaking of the chemical bonds within oxygen molecules O 2 by high-energy solar photons. This process, called photodissociation , results in the release of single oxygen atoms, which later join with intact oxygen molecules to form ozone.
Scientists believe that the formation of the ozone layer played an important role in the development of life on Earth by screening out lethal levels of UVB radiation ultraviolet radiation with wavelengths between and nanometres and thus facilitating the migration of life-forms from the oceans to land.
The amount of ozone in the stratosphere varies naturally throughout the year as a result of chemical processes that create and destroy ozone molecules and as a result of winds and other transport processes that move ozone molecules around the planet. Over the course of several decades, however, human activities substantially altered the ozone layer. Ozone depletion , the global decrease in stratospheric ozone observed since the s, is most pronounced in polar regions , and it is well correlated with the increase of chlorine and bromine in the stratosphere.
Those chemicals, once freed by UV radiation from the chlorofluorocarbons CFCs and other halocarbons carbon-halogen compounds that contain them, destroy ozone by stripping away single oxygen atoms from ozone molecules. Depletion is so extensive that so-called ozone holes regions of severely reduced ozone coverage form over the poles during the onset of their respective spring seasons. The largest such hole—which has spanned more than The Montreal Protocol has been a success, with some 99 percent of the ozone-depleting chemicals regulated by the treaty having been phased out since its adoption in Compliance with international treaties that phased out the production and delivery of many ozone-depleting chemicals, combined with upper stratospheric cooling due to increased carbon dioxide , is thought to have contributed to the shrinking of the ozone holes over the poles and to slightly higher stratospheric ozone levels overall.
Continued reductions in chlorine loading are expected to result in smaller ozone holes above Antarctica after However, some scientists noted that gains in stratospheric ozone levels have only occurred in the upper stratosphere , with declines in ozone concentrations in the lower stratosphere outpacing increases in the upper stratosphere.
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Donald Wuebbles Harry E. See Article History. The layers of Earth's atmosphere, with a yellow line showing the air temperature at various heights. Ozone damage on the leaf of an English walnut Juglans regia. Changes in the size of the ozone hole from October to October Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now. Antarctic ozone hole, September 17, Two bar graphs depicting the maximum ozone hole size and the minimum ozone coverage in Dobson units of the Southern Hemisphere ozone hole, — Researchers launching a balloon carrying an ozonesonde, an instrument that measures ozone in the atmosphere, at Amundsen-Scott South Pole Station in Antarctica.
Learn More in these related Britannica articles:. Sunlight causes nitric oxide to react chemically with ozone O 3 , thereby converting the ozone to molecular oxygen O 2. Equally important as an absorber in the longer wavelengths is water vapour. A secondary absorber in the infrared range is carbon…. History at your fingertips. Sign up here to see what happened On This Day , every day in your inbox! Email address. By signing up, you agree to our Privacy Notice.
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In the stratosphere the temperature of the atmosphere rises with increasing height, a phenomenon created by the absorption of solar radiation by the ozone layer. In the midlatitudes the peak concentrations of ozone occur at altitudes from 20 to 25 km about 12 to 16 miles. Peak concentrations are found at altitudes from 26 to 28 km about 16 to 17 miles in the tropics and from about 12 to 20 km about 7 to 12 miles toward the poles. The lower height of the peak-concentration region in the high latitudes largely results from poleward and downward atmospheric transport processes that occur in the middle and high latitudes and the reduced height of the tropopause the transition region between the troposphere and stratosphere. Near-surface ozone often results from interactions between certain pollutants such as nitrogen oxides and volatile organic compounds , strong sunlight , and hot weather.
Ozone depletion consists of two related events observed since the late s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere the ozone layer , and a much larger springtime decrease in stratospheric ozone around Earth's polar regions. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. The main cause of ozone depletion and the ozone hole is manufactured chemicals, especially manufactured halocarbon refrigerants , solvents , propellants , and foam- blowing agents chlorofluorocarbons CFCs , HCFCs, halons , referred to as ozone-depleting substances ODS. These compounds are transported into the stratosphere by turbulent mixing after being emitted from the surface, mixing much faster than the molecules can settle. Ozone depletion and the ozone hole have generated worldwide concern over increased cancer risks and other negative effects. The ozone layer prevents most harmful wavelengths of ultraviolet UV light from passing through the Earth's atmosphere. These wavelengths cause skin cancer , sunburn , permanent blindness, and cataracts , which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals.
Ozone depletion is allowing the UV radiation to earth surface. The exposure to these radiations is severely affecting all life forms on earth.
Emissions were increasing rapidly until the s. Since then the world has achieved rapid progress: the near-elimination of ozone-depleting substances and the trend towards recovery of the ozone layer are arguably among the most successful international environmental collaborations to date. In this entry we present the data on ozone layer depletion, signs of recovery, emissions of ozone-depleting substances, international agreement and collaboration, and the consequences of ozone layer depletion.
The ozone layer or ozone shield is a region of Earth 's stratosphere that absorbs most of the Sun 's ultraviolet radiation. It contains a high concentration of ozone O 3 in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is about 0. It was deduced that the missing radiation was being absorbed by something in the atmosphere. Eventually the spectrum of the missing radiation was matched to only one known chemical, ozone.
Но ведь у нас есть ТРАНСТЕКСТ, почему бы его не расшифровать? - Но, увидев выражение лица Стратмора, она поняла, что правила игры изменились. - О Боже, - проговорила Сьюзан, сообразив, в чем дело, - Цифровая крепость зашифровала самое. Стратмор невесело улыбнулся: - Наконец ты поняла.
- Весь мой план рухнет. Должен быть какой-то другой выход.
- Не нахожу. Как, вы сказали, имя девушки, которую нанял ваш брат. - Рыжеволосая, - сказал Беккер, уклоняясь от ответа. - Рыжеволосая? - переспросила. Пауза. - Это Servicio Social de Sevilla.
Сьюзан, в свою очередь, удивил ответ шефа. - Но ведь у нас есть ТРАНСТЕКСТ, почему бы его не расшифровать? - Но, увидев выражение лица Стратмора, она поняла, что правила игры изменились. - О Боже, - проговорила Сьюзан, сообразив, в чем дело, - Цифровая крепость зашифровала самое. Стратмор невесело улыбнулся: - Наконец ты поняла. Формула Цифровой крепости зашифрована с помощью Цифровой крепости. Танкадо предложил бесценный математический метод, но зашифровал .
April 5, Journal article Open Access.Reply
The depletion on the ozone layer results in the arrival of the ultraviolet radiation to the surface of the Earth introducing the risk of eye cancer.Reply
Do something for our planet, print this page only if needed.Reply