What is the term for liquid water that exists at temperatures below freezing?

Supercooled water is the term used to describe liquid water that remains in a liquid state even when temperatures drop below the freezing point. This phenomenon occurs because the water does not have enough nucleation points or impurities to initiate the freezing process. As a result, supercooled water can exist in a liquid form down to approximately -40 degrees Fahrenheit.

Understanding supercooled water is important, especially in aviation and weather contexts, as it can lead to dangerous conditions. For example, when supercooled droplets come into contact with an aircraft, they can freeze upon impact and create ice accumulation on the aircraft's wings and other surfaces, which can significantly affect its performance and safety.

In contrast, rime water typically refers to ice that forms when supercooled water freezes on contact with cold surfaces. Clear ice is usually associated with freeze precipitation, and mixed ice refers to a combination of different types of ice. These terms relate more to forms of ice rather than to the existence of liquid water below freezing temperatures. Thus, the selection of supercooled water accurately captures the essence of the phenomenon described in the question.