alijäähtyneisyys

Alijäähtyneisyys, also known as supercooling, is a phenomenon where a substance is cooled below its freezing point without becoming solid. This occurs when the substance remains in a liquid state despite the temperature being lower than its normal freezing point. This can happen if there are no nucleation sites present in the liquid, which are points where the solid phase can begin to form. Without these sites, the molecules do not have a structure to arrange themselves into a solid lattice.

When a supercooled liquid is disturbed, such as by shaking or introducing a seed crystal, it can rapidly solidify. This process is called nucleation and can release a significant amount of heat as the substance transitions from a liquid to a solid state. Alijäähtyneisyys is commonly observed in water, but it can occur in many other liquids as well.

The phenomenon has practical implications in various fields. In meteorology, alijäähtyneisyys is crucial for understanding cloud formation and precipitation processes, as water droplets in clouds can remain liquid even at temperatures well below freezing. It is also relevant in the food industry for freezing processes and in the development of antifreeze solutions, which work by lowering the freezing point of liquids and can also involve supercooling. The stability of supercooled liquids is a delicate balance, and the presence of impurities or external stimuli can trigger the phase transition.