Abstract: A method and apparatus is provided for production of ice nuclei by generation of homogenous nuclei in nozzle or orifice expansions. The homogeneous nuclei are formed in the rapid cooling of vapors by rapid expansion through a supersonic nozzle or an orifice. These nuclei then serve as seeding materials for formation of ice.A preferred method of carrying out the invention includes heating a volatile compound in a closed chamber to form a vapor, pressurizing the chamber with nitrogen gas and controllably releasing the resulting nitrogen gas-vapor combination through a nozzle or orifice in supersonic flow.