Haze, a slight clouding of the atmosphere caused by the suspension in the air of dust, soot, or other solid matter. Haze can also occur as a mixture of solid particles with tiny water droplets. A suspension consisting mostly or entirely of water droplets is a mist. A thick mist is a fog. Optical haze is caused by unevenly heated air that refracts light irregularly, causing distant objects to shimmer or waver.