Pekka makkonen - compact radio 96.7 mhz

Ice molecules can exhibit seventeen or more different phases ( packing geometries ) that depend on temperature and pressure. When water is cooled rapidly (quenching), up to three different types of amorphous ice can form depending on the history of its pressure and temperature. When cooled slowly correlated proton tunneling occurs below 20 K giving rise to macroscopic quantum phenomena . Virtually all the ice on Earth's surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice I h (spoken as "ice one h") with minute traces of cubic ice denoted as ice I c . The most common phase transition to ice I h occurs when liquid water is cooled below 0 °C ( K , 32 °F ) at standard atmospheric pressure . It may also be deposited directly by water vapor , as happens in the formation of frost. The transition from ice to water is melting and from ice directly to water vapor is sublimation .