Alterations in the quantity of atmospheric greenhouse gases determines the amount of solar energy retained by the planet, leading to global warming or global cooling. Aerosols are the tiny particles of liquid or dust suspended in the atmosphere. Some aerosols are a result of human activity, such as dust from agricultural activities, smoke from burning biomass and fossil fuels such as wood, and photochemically induced smog due primarily to vehicle emissions. The most important anthropogenically generated aerosol is sulphate from SO2 (produced from the burning of coal and oil). When held in the troposphere, aerosols reflect some of the sun’s radiation and thus have a negative forcing (cooling) effect. Aerosols may have a significant local or regional impact on temperature, but it can lead to hemispheric scale effects on climate patterns. Aerosols decrease the amount of solar energy reaching Earth's surface. Aerosols in the atmosphere increase haze, decrease visibility, and affect air quality.
In contrast to long-lived greenhouse gases, anthropogenic aerosols are very short-lived in the atmosphere, hence their radio active forcing adjusts rapidly to increases or decreases in emissions. Aerosols in the stratosphere may remain for years while in the troposphere, precipitation and interactions with Earth's surface remove aerosols in ten days or less.
2007-05-11 18:42:50
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answer #1
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answered by mahua 6
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