Water normally freezes at 273.15 K (0 °C or 32 °F), but it can be "supercooled" at standard pressure down to its crystal homogeneous nucleation at almost 224.8 K (−48.3 °C/−55 °F). ... Its glass transition temperature is much colder and harder to determine, but studies estimate it at about 136 K (−137 °C/−215 °F).

Why is water a supercooled liquid?

Supercooled water – that is, water that remains liquid far below its normal freezing point – does not have a uniform structure, but instead takes on two distinct forms. ... Unlike most other liquids, it is denser at ambient pressure than the ice it forms when it freezes.

How does water become supercooled?

When the temperature of the water is below freezing, the water has been supercooled. You can make the water freeze by pouring it over a piece of ice or by dropping a small piece of ice into the glass.