Ylijäähtyneinä

Ylijäähtyneinä is a Finnish term that translates to "supercooled" in English. It describes a liquid that has been cooled below its freezing point without solidifying. This state is metastable, meaning the liquid is not in its most stable form and can readily transition to a solid state if disturbed.

Supercooling occurs when a liquid is cooled slowly and without agitation, preventing the formation of nucleation sites. Nucleation sites are impurities or irregularities on the surface of a container or within the liquid itself where ice crystals can begin to form. Without these sites, the molecules in the liquid remain in a disordered, liquid state even at temperatures below their normal freezing point.

The transition from a supercooled liquid to a solid can be triggered by several factors. Mechanical shock, such as tapping the container or introducing a seed crystal, can provide the necessary energy for crystallization to begin. Changes in temperature or the introduction of an impurity can also induce solidification.

A common everyday example of supercooling can be observed with pure water. If distilled water is carefully cooled in a very clean container, it can remain liquid at temperatures below 0°C. Upon opening the container or adding an ice cube, the water can rapidly freeze. This phenomenon has practical applications in areas such as meteorology, where understanding supercooled water droplets in clouds is important for weather forecasting and aviation safety.