ozone layer or ozonosphere, region of the stratosphere stratosphere , second lowest layer of the earth's atmosphere. The level from which it extends outward varies with latitude; it begins c.5 1-2 mi (9 km) above the poles, c.6 or 7 mi (c.10 or 11 km) in the middle latitudes, and c.
..... Click the link for more information. containing relatively high concentrations of ozone ozone , an allotropic form of the chemical element oxygen (see allotropy). Pure ozone is an unstable, faintly bluish gas with a characteristic fresh, penetrating odor. The gas has a density of 2.144 grams per liter at STP.
..... Click the link for more information. , located at altitudes of 12–30 mi (19–48 km) above the earth's surface. Ozone in the ozone layer is formed by the action of solar ultraviolet light on oxygen.

The ozone layer prevents most ultraviolet (UV) and other high-energy radiation from penetrating to the earth's surface but does allow through sufficient ultraviolet rays to support the activation of vitamin D in humans. The full radiation, if unhindered by this filtering effect, would destroy animal tissue. Higher levels of radiation resulting from the depletion of the ozone layer have been linked with increases in skin cancers skin cancer, malignant tumor of the skin. The most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Rarer forms include mycosis fungoides (a type of lymphoma) and Kaposi's sarcoma.
..... Click the link for more information. and cataracts cataract, in medicine, opacity of the lens of the eye, which impairs vision. In the young, cataracts are generally congenital or hereditary; later they are usually the result of degenerative changes brought on by aging or systemic disease (diabetes).
..... Click the link for more information. and have been implicated in the decline of certain amphibian species.

In 1974 scientists warned that certain industrial chemicals, e.g., chlorofluorocarbons chlorofluorocarbons (CFCs), organic compounds that contain carbon, chlorine, and fluorine atoms. CFCs are highly effective refrigerants that were developed in response to the pressing need to eliminate toxic and flammable substances, such as sulfur dioxide and
..... Click the link for more information. (CFCs) and to a lesser extent, halons and carbon tetrachloride, could migrate to the stratosphere. There, sunlight could free the chlorine or bromine atoms to form chlorine monoxide or other chemicals, which would deplete upper-atmospheric ozone. A seasonal decrease, or "hole," discovered in 1985 in the ozone layer above Antarctica was the first confirmation of a thinning of the layer. The hole occurs over Antarctica because the extreme cold helps the very high clouds characteristic of that area form tiny ice particles of water and nitric acid, which facilitate the chemical reactions involved. In addition, the polar winds, which follow a swirling pattern, create a confined vortex, trapping the chemicals. When the Antarctic spring sun rises in August or September and hits the trapped chemicals, a chain reaction begins in which chlorine, bromine (from the halons), and ice crystals react with the ozone and destroy it very quickly. The effect usually lasts through November. There is a corresponding hole over the Arctic that similarly appears in the spring, although in some years warmer winters there do not result in a major depletion of the ozone layer. A global thinning of the ozone layer results as ozone-rich air from the remaining ozone layer flows into the ozone-poor areas.

Minimum ozone levels in the Antarctic decreased steadily throughout the 1990s, and less dramatic decreases have been found above other areas of the world. In 2000 (and again in 2003 and 2006) the hole reached a record size, extending over more than 10.5 million sq mi (27 million sq km), an area greater than that of North America. In 1987 an international agreement, the Montreal Protocol Montreal Protocol, officially the Protocol on Substances That Deplete the Ozone Layer, treaty signed on Sept. 16, 1987, at Montreal by 25 nations; 168 nations are now parties to the accord.
..... Click the link for more information. , was reached on reducing the production of ozone-depleting compounds. Revisions in 1992 called for an end to the production of the worst of such compounds by 1996, and CFC emissions dropped dramatically by 1993. Recovery of the ozone layer, however, is expected to take 50 to 100 years. Damage to the ozone layer can also be caused by sulfuric acid droplets produced by volcanic eruptions.

ozone layer

or ozonosphere

Region in the upper atmosphere, about 6–30 mi (10–50 km) high, with significant concentrations of ozone, formed by the effect of solar ultraviolet (UV) radiation on oxygen and also present in trace quantities elsewhere in earth's atmosphere. Ozone strongly absorbs solar UV radiation, causing atmospheric temperature to climb to about 30°F (0°C) at the top of the layer, and preventing much of this radiation from reaching earth's surface, where it would injure many living things. Chlorofluorocarbons, or CFCs, and some other air pollutants that diffuse into the ozone layer destroy ozone. In the mid-1980s, scientists discovered that a “hole”—an area where the ozone is up to 50% thinner than normal—develops periodically in the ozone layer above Antarctica. This severe regional depletion, explained as a natural seasonal depletion, appears to have been exacerbated by the effects of CFCs, and may have led to an increase in skin cancer caused by UV exposure. Restrictions on the manufacture and use of CFCs and other ozone-destroying pollutants were imposed in 1978.

ozone layer [′ō‚zōn ‚lā·ər]

(meteorology)

stratospheric ozone

Mentioned in	?		References in periodicals archive	?		Encyclopedia browser	?		Full browser	?
No references found			This third edition contains new practical examples in areas such as ozone layer depletion and nanotechnology. Elements of environmental engineering; thermodynamics and kinetics, ... by SciTech Book News The study, which includes the University of Colorado at Boulder and Embry-Riddle Aeronautical University, provides a market analysis for estimating future ozone layer depletion based on the expected growth of the space industry and known impacts of rocket launches. Rocket launches may need regulation to prevent ozone depletion by Asian News International INVESTIGATION AGENCY, TURNING UP THE HEAT: LINKAGES BETWEEN OZONE LAYER DEPLETION AND CLIMATE CHANGE: THE URGENT CASE OF HCFCs AND HFCS 2 (2006)); Lynn Anne Shapiro, Note, The Need for International Agreements Concerning the Ozone Depleting Effects of Chemical Rocket Propulsion, 4 S. Lessons from the Montreal Protocol: guidance for the next ... by Green, Bryan A. / Environmental Law			Ozery Ozhegov, Sergei Ozhegov, Sergei Ivanovich Ozherele Ozhogina Ozhogino Ozias Ozick, Cynthia Ozinki Ozma, Project Oznachennoe Ozni ozocerite Ozokerite Ozokerite Therapy Ozolin, Karlis Ozolin, Karlis Martynovich Ozolin, Nikolai Ozolin, Nikolai Georgievich Ozols, Janis Ozone ozone generator ozone hole ozone lamp ozone layer Ozone layer depletion ozonesonde Ozonide Ozonization ozonizer ozonolysis ozonosphere Ozragis Ozu Yasujiro Ozurgety Ozymandias Ozzie and Harriet P P band P blood group p chart P class P Cygni star P display p electron p orbital P pulse P shell P spot P wave P&G			Ozone Action Information Clearinghouse ozone alert ozone alert ozone alert Ozone and Water Vapor Group Ozone Depleting Containment Ozone Depleting Gas Index Ozone depleting substance Ozone Depleting Substance Substitute Ozone Depleting Substances Program Ozone Depleting Substances Reserve Ozone depletion Ozone depletion Ozone depletion Ozone depletion potential Ozone Dynamics Ultraviolet Spectrometer Ozone generator Ozone generator Ozone generator ozone hole ozone hole ozone hole ozone holes ozone holes ozone holes Ozone Isopleth Plotting with Optional Mechanisms ozone lamp ozone layer ozone layer ozone layer Ozone layer depletion Ozone Layer Protection Ozone Layer Protection Ordinance Ozone Layer Protection Unit Ozone Limiting Method Ozone Mapper and Profiler Suite Ozone Monitoring And Research Ozone Monitoring Instrument Ozone Monitoring Instrument Data Processing System Ozone Operations Resource Group ozone paper ozone shield ozone sickness ozone sickness Ozone Source Apportionment Technology Ozone therapy Ozone therapy Ozone therapy Ozone Therapy Training Program Ozone Transport Assessment Group Ozone Transport Commission Ozone Transport Region Ozone Widget Framework ozone-depleting Ozone-Depleting Chemical Ozone-Depleting Compound

ozone layer (redirected from Ozone layer depletion)

ozone layer

ozone layer
(redirected from Ozone layer depletion)