User guide

17
APPENDIX I RADIOMETRIC TERMINOLOGY
Term Explanation
Albedo The portion of incoming radiation which is reflected by a surface
Azimuth angle Angle in horizontal direction (0-360 °)
Angle of incidence Incident angle from zenith (vertical)
Cosine response Detector response according to the cosine law
Diffuse solar irradiance Solar radiation, scattered by water vapor, dust and other particles as
it passes through the atmosphere
Direct solar irradiance Radiation that has traveled a straight path from the sun
Global solar irradiance Total irradiance falling on a horizontal surface (Diffuse + Direct ⋅ cos α)
Irradiance Radiant flux density (W/m
2
)
Long-wave radiation Radiation with wavelengths > 4 μm and < 100 μm
Pyrheliometer Radiometer suitable to measure short-wave global radiation
Pyrgeometer Radiometer suitable to measure downward long-wave radiation
Pyrheliometer Radiometer suitable to measure direct irradiance
Short-wave radiation Radiation with wavelengths > 280 nm and < 4 μm
Thermopile Thermal detector made up of many thermocouple junctions
WMO World Meteorological Organisation
WRC World Radiation Center (in Davos, Switzerland)
WRR World Radiation Reference (standard radiation scale)
WSG World Standard Group (radiometer standards maintained in Davos)
Zenith angle Angle from zenith (0 °, vertical)