Which one of the following is the most important factor for the formul

Which one of the following is the most important factor for the formulation of smog?

[amp_mcq option1=”Formation of an ‘inversion lid'” option2=”Long winter nights” option3=”Presence of many air pollutant resources” option4=”Rapid fall in temperature with increasing height above the sea level” correct=”option1″]

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UPSC CDS-1 – 2022

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Smog is formed when pollutants (like smoke, sulfur dioxide, or vehicular emissions) combine with fog or react in the presence of sunlight (photochemical smog). A temperature inversion, forming an ‘inversion lid’, traps these pollutants close to the ground, preventing vertical mixing and dispersion. This concentration of pollutants significantly enhances the formation and severity of smog. While the presence of pollutants is necessary, their accumulation caused by the inversion is the most critical factor for formulation (concentration and reactions) of intense smog events.

Temperature inversion (inversion lid) is crucial for trapping pollutants near the surface, leading to high concentrations necessary for smog formation.

Normal atmospheric conditions involve temperature decreasing with height, promoting vertical air movement and dispersion of pollutants. An inversion layer is a layer where temperature increases with height, acting like a lid on the air below it. Long winter nights can contribute to stable conditions and ground-level inversions, but the inversion itself is the direct mechanism trapping pollutants. Rapid fall in temperature with height (normal lapse rate) disperses pollutants, preventing smog formation.

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