A Contribution to the Encyclopedia of Climate and Weather

Aerosols Aerosols are fine solid or liquid particles suspended in the atmosphere, where they reside typically for days to weeks before settling to the ground or being washed out by rain or snow. They arise both from natural sources (such as desert dust, sea spray and volcanic eruptions) and from human activities involving burning of fossil fuels and vegetation. Visible forms of atmospheric aerosol plumes include dust, smoke, smog and haze. Aerosol particles are small, but numerous, and often comprise of a number of inorganic and organic substances. They adversely affect human health, and thus are regulated as air pollutants. As an integral component of the Earth’s climate system, aerosols interact strongly with sunlight, and provide condensation nuclei for cloud formation. Man-made aerosols alter the climate in fundamental ways.