Ice was made oneThis article is about water ice. For the broader concept of "ices" as used in the planetary sciences, see volatiles. For other uses, see Ice (disambiguation).
A glacier is made from ice resulting from snow accumulation.
Frozen water in the form of an ordinary household ice cube. The white zone in the center is the result of tiny air bubbles.
Snowflakes by Wilson Bentley, 1902. Snow is ice that grows from water vapor in Earth's atmosphere, which is why it usually displays crystal shapes.
Ice (from the Old English "īs", in turn from the Proto-Germanic "*isaz") 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.
In the Solar System, ice occurs naturally from as close to the Sun as Mercury to as far as the Oort cloud. 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.
Ice molecules exhibit different phases (packing geometries) that depend on temperature and pressure. Virtually all the ice on Earth's surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice Ih (spoken as "ice one h"). The most common phase transition to ice Ih occurs when liquid water is cooled below 0°C (273.15K, 32°F) at standard atmospheric pressure. It may also be deposited by water vapor via sublimation, as happens in the formation of frost.
Ice is used in a variety of ways, including cooling, winter sports and ice sculpture.
2 Natural formation
2.1 Ice on the oceans
2.2 Ice on land and structures
2.3 Ice on rivers and streams...