. . "Cloud physics is the study of the physical processes that lead to the formation, growth and precipitation of atmospheric clouds. Clouds consist of microscopic droplets of liquid water (warm clouds), tiny crystals of ice (cold clouds), or both (mixed phase clouds). Cloud droplets initially form by the condensation of water vapor onto condensation nuclei when the supersaturation of air exceeds a critical value according to K\u00F6hler theory."@en . .