Överkylnning

Överkylnning, often translated as supercooling, is a phenomenon where a liquid is cooled below its freezing point without solidifying. This state is metastable, meaning the liquid remains liquid under normal conditions but can be easily induced to crystallize. The absence of nucleation sites, which are points where ice crystals can begin to form, is crucial for supercooling to occur. These sites can be microscopic impurities, rough surfaces, or even mechanical disturbances.

When a supercooled liquid is disturbed, such as by shaking or introducing a seed crystal, the nucleation process is initiated. This triggers rapid solidification, often releasing a significant amount of latent heat. The resulting ice can form very quickly, sometimes transforming the entire volume of liquid into a solid in a matter of seconds.

This phenomenon has several practical implications. In meteorology, supercooled water droplets are responsible for freezing rain and hail. In refrigeration and food preservation, supercooling can be used to chill products below their normal freezing point without ice crystal formation, which can damage cell structures. This can lead to improved texture and shelf life. However, uncontrolled supercooling in the environment can lead to dangerous conditions, particularly for aviation where supercooled water can freeze on aircraft surfaces. The study of supercooling is important for understanding phase transitions and developing new technologies in various fields.