Coagulation of Cloud Elements

the enlargement of cloud drops and crystals by coalescence or adhesion when they collide with one another (similar to the coagulation of aerosols).

Coagulation of cloud elements is due to a variety of factors that cause particles to collide. A distinction is made among Brownian coagulation, which results from chaotic thermal movement of particles; turbulent coagulation, which results from turbulent movement of individual particles of air; electrical coagulation, produced by opposite electric charges on the particles; and gravitational coagulation, caused by differences in the rate of fall of particles of different sizes and shapes. In nature, several mechanisms of coagulation of cloud elements usually act at the same time. This greatly complicates the process and its theoretical description. Gravitational coagulation plays a particularly important part in the enlargement of cloud particles and in precipitation.