A closed vessel in which the temperature, pressure, and humidity are controlled in a manner to cause cloud formation in the air within the enclosed space. Cloud chambers were used for early studies of high-energy particles such as cosmic rays (see Wilson cloud chamber). Meteorological versions have been used for studying cloud microphysical processes. They usually range in size from a few cubic centimeters to a few cubic meters, although cloud chambers as large as hundreds of cubic meters have been constructed.