waterfase

Waterfase is a term used in physics, chemistry and earth sciences to denote the state of water within a given system. It refers to the phase in which water exists, most commonly the three classical phases: solid (ice), liquid, and gas (water vapor). The waterfase of a system depends on temperature, pressure, and the presence of other substances, and may involve mixtures such as ice–water or liquid–vapor equilibria.

Phase transitions and diagrams describe how water changes phase. Under standard pressure, ice forms at 0°C, liquid water boils at 100°C, but the exact transitions shift with pressure. The water phase diagram shows regions where each phase is stable and lines representing fusion, vaporization, and sublimation. The triple point for pure water occurs at about 0.01°C and 611 pascals; the critical point is at about 647 kelvin and 22.064 megapascals. Knowledge of these boundaries helps explain phenomena from freezing to steam generation.

In natural and engineered systems, the waterfase influences properties such as permeability, heat transfer, humidity, and energy balance. In soils, it describes the fraction of pore space filled with water in its liquid or ice phase; in the atmosphere, it relates to vapor content, clouds and precipitation. Non-equilibrium and metastable states include supercooled water, superheated steam, and fog where different phases coexist.

Understanding waterfase is essential across disciplines such as meteorology, climatology, geology, civil and chemical engineering, and environmental science.