Atmospheric aerosols consist of small particles of liquid and solid material suspended in the air. Both natural and human-produced materials occur in the aerosol particles. Aerosol particles larger than about 1 micrometer in size are produced by processes such as windblown dust and sea salt from sea spray and bursting bubbles. Aerosols smaller than 1 micrometer are mostly formed by condensation processes such as conversion of sulfur dioxide gas to sulfate particles and by formation of soot and smoke during burning processes. After formation, the aerosols are mixed and transported by atmospheric motions and are primarily removed by cloud and precipitation processes.
