Kelvinmeting

Kelvinmeting is the process of determining thermodynamic temperature by expressing the result in kelvins (K), the SI unit of temperature. It covers the range from near absolute zero to very high temperatures, and is used in scientific research, metrology, and industry. The term is more common in Dutch-language contexts, where meting means measurement.

Kelvin is an absolute, thermodynamic temperature scale. Zero kelvin corresponds to absolute zero, the theoretical point where molecular motion is minimal. The kelvin scale is offset from Celsius by 273.15, so temperature in kelvins is simply temperature in Celsius plus 273.15. Unlike Celsius, kelvin values do not use negative numbers for natural temperature ranges in physics.

Measurement methods include primary thermometers and calibrated sensors: fixed-point cells, resistance temperature detectors (RTDs), thermistors, and thermocouples; optical and radiation thermometry for non-contact measurements; calibration against international scales such as ITS-90. Since 2019, the kelvin is defined by fixing the numerical value of the Boltzmann constant, aligning temperature measurement with fundamental physics.

Practical Kelvinmeting relies on traceability to the International System of Units (SI) through calibration chains. Uncertainty analyses quantify sources of error from instrumentation, environment, and method. Standards bodies publish procedures and reference data to ensure consistent temperature measurements across laboratories and industries.

Applications include laboratory research, industrial process control, cryogenics, semiconductors, climate research, and metrology. Kelvinmeting complements Celsius-based measurements by providing a physically rigorous temperature unit for precise thermodynamic work and comparisons across disciplines.