System of tiny liquid or solid particles evenly distributed in a finely divided state through a gas, usually air.
Aerosol particles participate in chemical processes and influence the electrical properties of the atmosphere. Though true aerosol particles range in diameter from a few nanometres to about one micrometre, the term is commonly used to refer to fog or cloud droplets and dust particles, which can have diameters of more than 100 micrometres. See also colloid ; emulsion .