The units and standards of temperature measurement are the cornerstone for ensuring the consistency and accuracy of global temperature measurement. In the International System of Units, Kelvin (K) is the basic unit. It is based on thermodynamic principles and is closely related to the microscopic thermal motion of matter. The thermodynamic temperature scale starts from absolute zero (0K), which is the temperature at which the thermal motion of matter molecules theoretically completely stops.
Celsius (℃) is a unit widely used in our daily lives and scientific research. The conversion relationship between it and Kelvin is: T(K) = t(℃) + 273.15. This conversion relationship enables us to conveniently convert between different temperature measurement systems.
In the long process of establishing temperature measurement standards, scientists have used various theories and methods. The ideal gas temperature scale is an important theoretical basis in the early stage. It uses the relationship between pressure, volume and temperature of an ideal gas to define temperature. However, there is a deviation between actual gas and ideal gas, which has promoted the development of more accurate thermodynamic temperature scales.
The triple point temperature of water is strictly defined as 273.16K, which is a milestone standard point. Based on this, national metrology institutions can calibrate various temperature measuring instruments through complex calibration devices and technologies. For example, in national-level metrology laboratories, the triple point temperature of water is accurately reproduced through high-precision constant temperature baths and standard thermometers, and then compared with the thermometer to be calibrated to adjust its scale and accuracy, thereby ensuring the accuracy of these thermometers in measuring temperature in different environments. The determination of these standards and units has established a unified framework for temperature measurement on a global scale, making the temperature measurement data in various fields comparable and reliable.
