Temperature Ocean Water, which is water specially prepared with a specified blend of hydrogen and oxygen isotopes. Absolute zero is defined as precisely and . It is the temperature at which all classical translational motion of the particles comprising matter ceases and they are at complete rest in the classical model. Quantum-mechanically, however, zero-point motion remains and has an associated energy, the zero-point energy. Matter is in its ground state, and contains no thermal energy. The triple point of water is defined as and . This definition serves the following purposes: it fixes the magnitude of the kelvin as being precisely
Absolute scale measurements of absolute pressure from weather forecasts, most pressures such as tire pressures and water pressures are measured relative to atmospheric pressure using cheaper and simpler pressure gauges. For this reason, the pressure relative to atmospheric pressure is called gauge pressure and measurements given in units like pounds per square inch (abbreviated lbf/in or psi) are often shown as "psig" (the "g" standing for gauge) or "psia" ("a" for absolute). Absolute scales are used when precise values are needed in comparison to a natural, unchanging zero point. Measurements of length, area and volume are inherently absolute, although measurements of distance