Its shape is so regularly three-cornered, that Triangle or triple-point (Trinacria) was one of its ancient names.
triple point n.
The temperature and pressure at which three different phases, such as gaseous, liquid, and solid phases, of a particular substance can coexist in equilibrium.
|triple point |
The temperature and pressure at which a substance can exist in equilibrium in the liquid, solid, and gaseous states. The triple point of pure water is at 0.01°C (273.16K, 32.01°F) and 4.58 mm (611.2Pa) of mercury and is used to calibrate thermometers. Compare critical point.