Termometriikka

Termometriikka, or thermometry, is the science and practice of measuring temperature. It encompasses the development, calibration, and use of instruments that quantify thermal states across science, medicine, industry, and meteorology. Temperature is a fundamental physical quantity related to molecular energy; a thermometric instrument converts this quantity into a measurable signal such as a liquid volume, electrical resistance, thermoelectric emf, or infrared radiation.

Measurement methods range from contact to non-contact. In contact thermometry, sensors touch the object or medium being measured. Examples include liquid-in-glass thermometers (mercury or alcohol), bimetallic strips, resistance thermometers (RTDs like platinum), thermistors, and thermocouples. Non-contact thermometry relies on emitted infrared radiation or optical properties to infer temperature, enabling rapid measurements without contact and in hazardous or inaccessible environments.

Calibration and traceability are central to termometriikka. Thermometers are calibrated against fixed points or calibrated references, with uncertainties estimated in an uncertainty budget. International standards such as ITS-90 provide reference scales and procedures for many thermometry applications. Measurements are reported in degrees Celsius or Kelvin, with conversions to other scales as needed, and traceability to the International System of Units (SI) is maintained through accredited laboratories.

Applications span medicine, industrial process control, food safety, climate research, and meteorology. Common instruments include clinical thermometers, industrial RTDs and thermocouples, infrared thermometers, and specialized liquid-in-glass devices. Limitations include range, response time, environmental conditions, and, in older devices, hazardous materials.