International Temperature Scale of 1990 International Temperature Scale of 1990 The International Temperature Scale of 1990 (ITS–90) published by the Consultative Committee for Thermometry (CCT) of the International Committee for Weights and Measures (CIPM) is an equipment calibration standard for making measurements on the Kelvin and Celsius temperature scales. ITS–90 is an approximation of the thermodynamic temperature scale that facilitates the comparability and compatibility of temperature measurements internationally. It specifies fourteen calibration points ranging from 0.65±0 K to ±0 K (−272.50±0 °C to ±0 °C) and is subdivided into multiple temperature ranges which overlap in some instances. ITS–90 is the latest (as of 2014) of
Temperature cool a system to absolute zero, all classical motion of its particles would cease and they would be at complete rest in this classical sense. Microscopically in the description of quantum mechanics, however, matter still has zero-point energy even at absolute zero, because of the uncertainty principle. Temperature is a measure of a quality of a state of a material. The quality may be regarded as a more abstract entity than any particular temperature scale that measures it, and is called "hotness" by some writers. The quality of hotness refers to the state of material only in a particular locality,