All objects with a temperature above absolute zero emit electromagnetic radiation. The wavelengths and intensity of radiation emitted are related to the temperature of the object. Infrared radiometers are sensors that measure infrared radiation, which is used to determine surface temperature without touching the surface (when using sensors that must be in contact with the surface, it can be difficult to maintain thermal equilibrium without altering surface temperature). Infrared radiometers are often called infrared thermometers because temperature is the desired quantity, even though the sensors detect radiation.
Typical applications of infrared radiometers include:
- plant canopy temperature measurement for use in plant water status estimation
- road surface temperature measurement for determination of icing conditions
- terrestrial surface (soil, vegetation, water, snow) temperature measurement in energy balance studies