Meaning: A treeless grassy plain. Classified under: Nouns denoting spatial position. Hypernyms (prairie is a kind of...): grassland (land where grass or grasslike vegetation grows and is the dominant form of plant life). Instance hyponyms:
In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium. For example, the triple point of mercury occurs at a temperature of â38.83440 Â°C and a pressure of 0.2 m Pa.
In addition to the triple point for solid, liquid, and gas phases, a triple point may involve more than one solid phase, for substances with multiple polymorphs. Helium-4 is a special case that presents a triple point involving two different fluid phases (lambda point).