Ice is water frozen into a solid state. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions. The addition of other materials such as soil may further alter its appearance.
Ice appears naturally in forms of snowflakes, hail, icicles, ice spikes and candles, glaciers, pack ice, frost, and polar ice caps. It is an important component of the global climate and plays an important role in the water cycle. Furthermore, ice has numerous cultural applications, from ice cooling of drinks to winter sports to the art of ice sculpting.
The molecules in solid ice may be arranged in numerous different ways, called phases, depending on the temperature and pressure. Typically, ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on Earth's surface 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 can also deposit from vapour with no intervening liquid phase, such as in the formation of frost.