Alijäähtynyt

Alijäähtynyt, a Finnish term, translates to "supercooled" in English. It describes a liquid that has been cooled below its freezing point without solidifying. This metastable state occurs when the liquid is pure and free from nucleation sites, which are surfaces or impurities that can initiate crystal formation. Without these sites, the molecules of the liquid remain in a disordered state even at temperatures where they would typically form a solid structure.

Supercooling is a common phenomenon observed in water. If pure water is carefully cooled in a clean container, it can remain liquid at temperatures as low as -40 degrees Celsius. However, any disturbance, such as shaking the container or introducing a tiny ice crystal, can trigger rapid solidification. This is because the disturbance provides the necessary nucleation site for the molecules to arrange themselves into a solid lattice.

The concept of alijäähtynyt is relevant in various scientific and natural contexts. In meteorology, supercooled water droplets are responsible for phenomena like freezing rain and graupel. When these supercooled droplets encounter a surface or an object, they freeze instantly, forming a layer of ice. Understanding supercooling is also important in fields like cryogenics, food science, and materials science, where controlling the freezing process is crucial.