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Definition: smog from The Penguin Dictionary of Science

Smoke-filled fog that pollutes the air over cities. The London smogs were notorious until the Clean Air Act of 1956. Photochemical smog, a brown haze containing a complex cocktail of molecules such as nitrogen dioxide created by reactions initiated by the absorption of sunlight, remains a problem in some cities, such as Los Angeles.


smog

From The Columbia Encyclopedia
(smŏg) [ sm oke+f og ], dense, visible air pollution . Smog is commonly of two types. The gray smog of older industrial cities like London and New York derives from the massive combustion of coal and fuel oil in or near the city, releasing tons of ashes, soot, and sulfur compounds into the air. The brown smog characteristic of Los Angeles and Denver in the late 20th cent. is caused by automobiles. Nitric oxide from automobile exhaust combines with oxygen in the air to form the brown gas nitrogen dioxide. Also, when hydrocarbons and nitrous oxides from auto emissions are exposed to sunlight, a photochemical reaction takes place that results in the formation of ozone and other irritating compounds. In some instances, atmospheric pollutants accumulate and become concentrated when air movement is stopped by a temperature inversion : Usually the air is warmer at the earth's surface and colder above; in a temperature inversion a layer of warm air forms above and holds down a layer of cool…
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Smog obscures the south‐east coast of China,...
Smogs occur when pollutants accumulate in a shallow layer of cold air trapped under warmer air (a situation known as a temperature inversion). Where poor‐quality coals are used widely, as in Eastern Europe, sulphurous smogs often envelop cities in cold winters. The London smog event of December 1952…
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Full text Article smog

From The Columbia Encyclopedia
(smŏg) [ sm oke+f og ], dense, visible air pollution . Smog is commonly of two types. The gray smog of older industrial cities like London and New York derives from the massive combustion of coal and fuel oil in or near the city, releasing tons of ashes, soot, and sulfur compounds into the air. The…
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Full text Article smog

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Natural fog containing impurities, mainly nitrogen oxides (NO x ) and volatile organic compounds (VOCs) from domestic fires, industrial furnaces, certain power stations, and internal-combustion engines (petrol or diesel). It can cause substantial illness and loss of life, particularly among chronic…
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Full text Article smog

From Dictionary of Energy
Smog is not a very recent phenomenon: The term, a contraction of smoke and fog, was introduced in 1905 by Dr. H.A. des Vœux, to describe the mixture of soot, sulphuric acid and other pollutants caused by the emissions of many coal furnaces in London, which has affected the population of that city…
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Full text Article Smog

From Brewer's Dictionary of Modern Phrase and Fable
A linguistic and literal blend of smoke and fog, as an insidious form of polluted air. The word appears to have been first used in 1905 by H.A. des Vœux of the Coal Smoke Abatement Society to describe atmospheric conditions over British towns. It was popularized by his report to the Manchester…
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From Black's Veterinary Dictionary
A word produced by combining smoke and fog. It is the popular name for fog containing a dangerously high proportion of sulphur dioxide, other harmful gases and soot particles derived from coal fires and factory chimneys, usually in the colder months of the year. It is often yellow in colour. Smog…
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From Britannica Concise Encyclopedia
Polluted air over a community. The term, a combination of “smoke” and “fog,” was popularized in the early 20th century and now commonly refers to the pall of automotive or industrial origin that lies over many cities. Sulfurous smog results from the use of sulfur-bearing fossil fuels, particularly…
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Full text Article Smog

From Brewer's Dictionary of Phrase and Fable
A linguistic and literal blend of ‘smoke’ and ‘fog’, as an insidious form of polluted air. The word appears to have been first used in 1905 by H.A. des Voeux of the Coal Smoke Abatement Society to describe atmospheric conditions over British towns. It was popularized by his report to the Manchester…
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When a layer of warm air lies over a city like Los Angeles, it can trap thick, pollutant-rich air near the ground, a form of pollution we call smog. In the usual course of things, the sun warms Earth, and that warm air expands and rises. It cools as it rises, losing about 3.5 degrees Fahrenheit with…
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From The New Dictionary of Cultural Literacy, Houghton Mifflin
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