Smoke clouds used for screening purposes. Traditionally, smoke is defined as a visible aerosol (that is, a suspension of solid or liquid particles in a gas) resulting from incomplete combustion. Military screening smokes are a special case. They are generally composed of liquid droplets with a mean particle size around 1 micrometer, and produce a bright white cloud of long duration. The effectiveness of these aerosols results from their size and composition. The individual aerosol particles efficiently scatter light in all directions. This scattering, known as Mie scattering, reduces the intensity of any light passing through the cloud and produces considerable glare, the white cloud effect, to reduce the target-to-background contrast.