triple points

Noun

triple point (plural triple points)

1. The unique temperature and pressure at which the solid, liquid and gas phases of a substance are all in equilibrium.
   • A solid sublimes only when the pressure of its vapor is below that of the triple point for that substance.2006, David B. Troy, Paul Beringer, Remington: The Science and Practice of Pharmacy, →ISBN, page 179
2. A point where the incident shock wave, the reflected shock wave, the Mach stem, and one slipstream meet.
   • When the incident shock wave is at position “a” the second triple point, T, is still inside the zone where the vibrational degree of freedom has not yet reached its equilibrium and the dissociational degree of freedom is still frozen at that position, as its excitation can be assumed to start only...2007, Gabi Ben-Dor, Shock Wave Reflection Phenomena, →ISBN, page 198
3. A point where a curve or surface intersects itself along three arcs.
   • The number of the distinguished edges whose orientations point towards the triple point is exactly one, or exactly two.1998, J. Scott Carter, Masahico Saito, Knotted Surfaces and Their Diagrams, →ISBN, page 162
4. The intersection of an occluded front, cold front, and warm front.
   • A further investigation is made of the reasonably-close relationship between some multiple tornado outbreaks in the British Isles and the passage of frontal-system triple points (TPs) using, principally, TORRO records and the hourly British Isles charts archived by the Meterorological Office at...1993, Meteorological and Geoastrophysical Abstracts
5. The point where two boundaries, such as a dry line, outflow boundary, or cold front, intersect.
   • Few, however, reach the African continent; some dissipate in the intertropical-front bulge east of southern Africa; others form triple points with the temperate fronts available for recurving anywhere between Australia and the Seychelles-Madagascar-Mascarenes (Reunion-Mauritius-Rodriguez) sector.1947, Maurice Adolph Garbell, Tropical and Equatorial Meteorology, page 205
6. (plate tectonics) A point where three plates intersect.
   • Such a 'piecrust model' has been used to explain the generation of triple points which can give rise to splitting of a continental body.2003, Neville Price, Major Impacts and Plate Tectonics, →ISBN, page 131