ozonosphere


ozonosphere
ozonosphere [ō zō′nə sfir΄]
n.
/span> OZONE + -SPHERE

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o·zo·no·sphere (ō-zōʹnə-sfîr') n.   o·zo'no·spherʹic (-sfîrʹĭk, -sfĕrʹ-) or o·zo'no·spherʹi·cal (-ĭ-kəl) adj.

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 region in the upper atmosphere between about 10 and 50 km (6 and 30 miles) in altitude, in which there are appreciable concentrations of ozone and in which the temperature distribution is largely determined by the radiative properties of ozone.

      Ozone has the formula O3; it is always present in trace quantities in the Earth's atmosphere, but its largest concentrations are in the ozonosphere. There it is formed primarily as a result of shortwave solar ultraviolet radiation (wavelengths shorter than 242 nanometres), which dissociates normal molecular oxygen (O2) into two oxygen atoms. These oxygen atoms then combine with nondissociated molecular oxygen to yield ozone. Ozone, once it has been formed, can also be easily destroyed by solar (solar radiation) ultraviolet radiation of wavelengths less than 300 nanometres.

      Because of the strong absorption of solar ultraviolet radiation by molecular oxygen and ozone, solar radiation capable of producing ozone cannot reach the lower levels of the atmosphere, and the photochemical production (photochemical reaction) of ozone is not significant below about 20 km (12 miles). This absorption of solar energy is very important in producing a temperature maximum at about 50 km, called the stratopause, or the mesopeak. Also, the presence of the ozone layer in the upper atmosphere, with its accompanying absorption, effectively blocks almost all solar radiation of wavelengths less than 290 nanometres from reaching the Earth's surface, where it would injure or kill most living things.

      Certain air pollutants, particularly chlorofluorocarbons (chlorofluorocarbon) and halons (halon) (chlorofluorobromine compounds), can diffuse into the ozonosphere and destroy ozone. In the mid-1980s scientists discovered that a “hole” developed periodically in the ozonosphere above Antarctica; it was found that the ozone layer there was thinned by as much as 40–50 percent from its normal concentrations. This severe regional ozone depletion was explained as a natural phenomenon, but one that was probably exacerbated by the effects of chlorofluorocarbons and halons. Concern over increasing global ozone depletion led to international restrictions on the use of chlorofluorocarbons and halons and to scheduled reductions in their manufacture.

      Even though the ozone layer is about 40 km (25 miles) thick, the total amount of ozone, compared with more abundant atmospheric gases, is quite small. If all of the ozone in a vertical column reaching up through the atmosphere were compressed to sea-level pressure, it would form a layer only a few millimetres thick.

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Universalium. 2010.

Look at other dictionaries:

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  • ozonosphere — [ō zō′nə sfir΄] n. [< OZONE + SPHERE] OZONE LAYER …   English World dictionary

  • ozonosphere — ozonosfera statusas T sritis fizika atitikmenys: angl. ozonosphere vok. Ozonosphäre, f rus. озоносфера, f pranc. ozonosphère, f …   Fizikos terminų žodynas

  • ozonosphère — ozonosfera statusas T sritis fizika atitikmenys: angl. ozonosphere vok. Ozonosphäre, f rus. озоносфера, f pranc. ozonosphère, f …   Fizikos terminų žodynas

  • Ozonosphère — Couche d ozone Les différentes couches de l atmosphère terrestre …   Wikipédia en Français

  • ozonosphere — ozono sluoksnis statusas T sritis chemija apibrėžtis 15–50 km virš Žemės paviršiaus esantis atmosferos sluoksnis, kuriame susikaupusi didžioji atmosferos ozono dalis. atitikmenys: angl. ozone layer; ozonosphere rus. озоновый слой …   Chemijos terminų aiškinamasis žodynas

  • ozonosphere — ozono sluoksnis statusas T sritis ekologija ir aplinkotyra apibrėžtis Žemės atmosferos sluoksnis (20–50 km virš jūros lygio), kuriame yra didesnė ozono koncentracija. Didžiausias ozono tankis yra ozonosphere25 km aukštyje. Ozono sluoksnis sugeria …   Ekologijos terminų aiškinamasis žodynas

  • ozonosphere — noun Date: 1933 ozone layer …   New Collegiate Dictionary

  • ozonosphere — noun A layer in part of the stratosphere that has a larger than normal concentration of ozone; the ozone layer …   Wiktionary

  • ozonosphere — The general stratum of the upper atmosphere in which there is an appreciable ozone concentration and ozone plays an important part in the radiative balance of the atmosphere. It lies roughly between 6 and 30 miles (10–50 km), with the maximum… …   Aviation dictionary


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