In meteorological terms, pyrgeometers are used to measure “downward and upward longwave irradiance”. Longwave radiation is the part of radiation that is not emitted by the sun.
Hukseflux pyrgeometers are suitable for day-and-night longwave irradiance measurements in meteorological applications. Our instruments can be heated, which improves measurement accuracy as it prevents dew deposition on its window. Because of features like this, model IR02 is popular and often used in agricultural networks. IR20 is a research grade pyrgeometer suitable for high-accuracy longwave irradiance measurements in climatological networks, in uncertainty assessments and as a calibration reference (IR20WS).