Ylijäähtymiseksi

Ylijäähtymiseksi is a Finnish term that translates to "supercooling" in English. It describes the phenomenon where a liquid is cooled below its freezing point without solidifying. This is possible because the formation of ice crystals requires a nucleation site, which is a surface or impurity on which the crystal can begin to grow. If a liquid is cooled very slowly and carefully, and if it is free from impurities, it can remain in a liquid state even at temperatures below its normal freezing point.

When a supercooled liquid is disturbed, for example by shaking it or introducing a nucleation site, it can rapidly freeze. This sudden solidification releases latent heat, which can cause the temperature of the liquid to rise back to its freezing point. Supercooling is a common phenomenon observed in water, but it can occur in many other liquids as well.

Applications of supercooling include its use in artificial snowmaking, where water is sprayed into cold air and allowed to supercool before impacting a surface, promoting rapid freezing. It also plays a role in the formation of hailstones in the atmosphere and in some laboratory experiments where precise control over crystallization is desired. Understanding supercooling is important in various scientific and industrial processes, from food preservation to materials science.