What is “Aerosol”?
Aerosols are liquid or solid particles suspended in the air. A primary aerosol has particles that are introduced directly into the gas and secondary aerosols are formed when gas-to-particle conversion occurs.
The size of particles has a major influence on their properties. The aerosol particle radius or diameter is a key property used to characterize aerosols.
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- Industrial dust, anthropogenic aerosols Transportation, coal combustion, cement manufacturing, metallurgy, and waste incineration are among the industrial and technical activities that produce anthropogenic primary aerosols.
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[Fig.1] anthropogenic aerosols
reference : wikipedia
Various Radiative Mechanisms of Aerosols
[Fig.2] the various radiative mechanisms associated with cloud effects in relation to aerosols
reference : IPCC Fourth Assessment Report: Climate Change 2007
Direct effect
The direct effect is the mechanism by which aerosols scatter and absorb shortwave and longwave radiation, thereby altering the radiative balance of the Earth-atmosphere system.
[Fig.3] single scattering Albedo of aerosols
reference : Aerosols, their Direct and Indirect Effects, J.E. Penner
Aerosols with diameters between about 0.1 and 2 μm scatter the most light per unit mass. The direct radiative effect of aerosols is sensitive to the single scattering albedo ωo. For example, a change in ωo from 0.9 to 0.8 can often change the sign of the direct effect, depending on the Albedo of the underlying surface and the altitude of the aerosols.
[Table.1] Variation in dry aerosol optical properties by region/type
reference : Aerosols, their Direct and Indirect Effects, J.E. Penner
*Albedo
Albedo is reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it. The average overall Albedo of Earth is 0.30 to 0.35, because of clouds.
