<P> Ice is water frozen into a solid state . Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish - white color . </P> <P> In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far away as the Oort cloud objects . Beyond the Solar System, it occurs as interstellar ice . It is abundant on Earth's surface--particularly in the polar regions and above the snow line--and, as a common form of precipitation and deposition, plays a key role in Earth's water cycle and climate . It falls as snowflakes and hail or occurs as frost, icicles or ice spikes . </P> <P> Ice molecules can exhibit eighteen 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 (− 253 ° C) 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 (spoken as "ice one h") with minute traces of cubic ice denoted as ice I . The most common phase transition to ice I occurs when liquid water is cooled below 7002273149999999999 ♠ 0 ° C (7002273149999999999 ♠ 273.15 K, 7002273149999999999 ♠ 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 . </P> <P> Ice is used in a variety of ways, including cooling, winter sports and ice sculpture . </P>

At what temperature does water turn into ice in degree celsius