instrument for measuring the intensity of solar irradiance
NOTE 1 See also IEV 845-05-06
NOTE 2 Commonly, a radiometer is a thermal instrument using thermocouples or thermopiles and is independent of wavelength
a) absolute radiometer
radiometer that can measure or calculate the absolute quantity of radiant power based on physical laws and the known physical constants of its components
b) pyranometer
radiometer normally used to measure global irradiance on a horizontal plane
NOTE 3 A pyranometer can also be used to measure diffuse irradiance when used with a shade ring or disc
NOTE 4 A pyranometer can also be used to measure total irradiance on an inclined plane, which would include radiation reflected from the foreground
c) pyrheliometer
radiometer, including with a collimator, used to measure direct irradiance
NOTE 5 A pyrheliometer is sometimes called a normal incidence pyrheliometer, or NIP
d) spectroradiometer
instrument used to measure spectral irradiance distribution of an incident radiation as the function of wavelength |