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Centigrade temperature scale

Centigrade temperature scale

The fundamental scale of temperature is the absolute thermodynamic centigrade scale with the ice point at 0° and the equilibrium between liquid water and its vapour at the pressure of one standard atmosphere at 100°. The scale of the helium gas thermometer (variation of pressure of a fixed volume of gas) is as close as possible to the thermodynamic scale. Conforming to ISO R 31 part IV recommendation it is defined as t c: t c = T - 273.16, T being the thermodynamic temperature. (526)