2. Cirrus One of three basic cloud forms; also one of the three high cloud types; they are thin, delicate ice-crystal often appearing as veil-like patches or thin, wispy fibers.
3. Cumulus One of three basic cloud forms; also the name given to one of the clouds of vertical development; they are billowy individual cloud masses that often have flat bases.
4. Stratus One of three basic cloud forms; they are sheets or layers that cover much or all of the sky.
5. Bergeron Process A theory that relates the formation of precipitation to supercooledclouds, freezing nuclei, and the different saturation levels of ice and liquid water.
6. Supercooled Water The condition of water droplets that remain in the liquid state at temperatures well below O˚C.
7. Supersaturated Air The condition of air that is more highly concentrated than is normally possible under given temperature and pressure conditions; when describing humidity, it refers to a relative humidity that is greater than 100 percent.
8. Collision-Coalescence Process A theory of raindrop formation in warm clouds in which large cloud droplets collide and join together to form with smaller droplets to a raindrop; opposite electrical charges may bind the cloud droplets together.
