A supersaturated solution is a solution that contains more of the dissolved material than could be dissolved by the solvent under existing circumstances.
Air that is supersaturated with water may upon being disturbed as by an atomic particle precipitate water droplets showing the path of the particle, a cloud chamber. In the more general context a cloud may form.
Precipitation of a dissolved solid in a supersaturated solution may be triggered by the addition of a seed crystal.
Supersaturated solutions are prepared or result when as much as possible is dissolved then the condition of the solvent is changed, for example by a reduction in temperature or volume as by evaporation.