Jäätyminen

Jäätyminen, commonly translated as freezing, is the process by which a liquid becomes a solid as thermal energy is removed and its temperature reaches or falls below the substance’s freezing point. In ideal conditions, pure liquids crystallize at a characteristic temperature; in practice impurities, interfaces, and pressure can modify when and how crystallization begins. Liquids can also become supercooled, staying liquid below their freezing point until a nucleation event initiates solidification. The transition releases latent heat of fusion as the material forms a solid lattice.

Freezing has wide relevance across natural and engineered contexts. In food preservation, freezing slows enzymatic activity and microbial growth, helping to extend shelf life. Ice crystal formation can damage cells and tissues, influencing texture and quality upon thawing. In cryobiology and medicine, controlled cooling and cryoprotectants are used to preserve cells, tissues, and sometimes whole organs; vitrification aims to avoid ice crystals by forming an amorphous solid rather than crystalline ice.

In nature, freezing shapes climate and geography, producing frost, ice on lakes, and soil permafrost. Some organisms avoid damage through antifreeze proteins, accumulation of compatible solutes, or by tolerating supercooling. Environmental freezing also interacts with ecosystems, weather patterns, and seasonal cycles.

Practical considerations include safe handling of frozen foods, proper thawing to minimize quality loss and bacterial growth, and recognizing that rapid temperature changes can cause stress or damage in materials and structures.