Kiteytyminen

Kiteytyminen is the Finnish term for condensation, a physical process in which a substance transitions from a gaseous to a liquid state. The phenomenon occurs when the temperature of a vapor falls below its dew point or when its pressure rises above the saturation pressure, causing the vapor molecules to lose kinetic energy and coalesce into liquid droplets. In the atmosphere, kiteytyminen is responsible for the formation of clouds, fog, and dew, and it plays a central role in the water cycle by returning water vapour to the Earth's surface.

The underlying mechanism involves nucleation, where microscopic particles such as dust, pollen or sea salt serve as condensation nuclei. On these surfaces, water molecules can aggregate more readily, reducing the energy barrier required for phase change. When sufficient droplets form, they may grow by further condensation or by colliding and merging with other droplets—a process known as coalescence.

Kiteytyminen is also relevant in industrial and technological contexts. In refrigeration and air‑conditioning systems, it is exploited to remove heat from a space by evaporating a refrigerant and then condensing it in a heat exchanger. In power generation, steam turbines rely on the condensation of exhaust steam to maintain efficiency. Chemical engineering uses controlled condensation to separate components in distillation columns and to recover solvents.

Thermodynamically, condensation is an exothermic process: latent heat is released as the substance changes phase. This released heat can affect surrounding temperatures and must be managed in engineered systems to prevent overheating. Understanding kiteytyminen is therefore essential in meteorology, environmental science, and various engineering disciplines.