The body of knowledge concerned with physical properties of clouds in the atmosphere and the processes occurring therein. Cloud physics, broadly considered, embraces not only the study of condensation and precipitation processes in clouds, but also radiative transfer, optical phenomena, electrical phenomena, and a wide variety of hydrodynamic and thermodynamic processes peculiar to natural clouds. Cloud physics is a distinct subdivision of physical meteorology. Early interest in this subject was stimulated by the role of clouds in aircraft safety related to icing and turbulence (The Thunderstorm Project) and the discovery of cloud modification techniques by cloud seeding. The formation of precipitation and the influence of clouds in radiative processes in the atmosphere (both solar and thermal) determine the key role of the subject in global climate.