Aerosols

AEROSOLS ARE SOLID or liquid particles that are small enough to remain suspended in the atmosphere for hours to days. They are created by both natural and human-caused processes, and are either directly emitted from sources or are formed in the atmosphere from the condensation of gases. Aerosols can perturb climate either directly, by the scattering or absorption of radiation, or indirectly, through the modification of clouds and precipitation. The effects of aerosols on climate represent the single largest source of uncertainty in the understanding of global warming. While the magnitude of the effect is unclear, most observations and models agree that the impact of aerosols is to cool the earth.

Typically, particles that comprise aerosols range in size from the length of a large molecule ...