Haze

The term haze is understood in meteorology or a hydro - Lithometeor in which the Earth's atmosphere is clouded by water droplets or solid suspended particles. A haze accumulation over cities is everyday language also known as smog or haze hood.

In contrast to the mist is much less dense, with a visibility of more than one kilometer. From a visibility of eight or more kilometers, the turbidity is too weak to speak of haze, which you already attaches this limit in some cases with a visibility of five kilometers. In addition to this optical characteristic can be both phenomena by physically different, that it is with water vapor saturation of the air to fog and unsaturated air by mist. Like the fog and in contrast to a cloud haze has always ground. Especially in the seafaring one speaks instead of haze by hazy weather.

Mist formed, normally by condensation of the water vapor contained in the air if the humidity is high enough for this purpose and a sufficiently large number of aerosol particles present. The latter act as condensation nuclei and are essential for the formation of droplets on heterogeneous nucleation, can also appear even as vapor in sufficient concentration, however, which is then called a dry haze. Defining boundary between the wet and dry vapor which always contains a certain amount of moisture, is at a relative humidity of 80%. In addition, one speaks of dust haze, if some of the suspended particles are large enough to make them visible to the eye can.

Condensation below the saturation point occurs due to the hygroscopic properties of the aerosol particles. However, the droplets can grow it only as far as the ability of the particles to bind moisture, is not compensated by the increasing influence of surface forces. The maximum possible droplet size is therefore limited, and usually is in the range of 0.1 to 1 microns.

Dunst - and especially dry vapor - created especially for inversion conditions, ie when the vertical exchange of air is interrupted. In urban areas where the air contains this occurs then sometimes in the form of smog, which still represents a haze even with visibility below one kilometer.