Why is the Pyrgeometer from Kipp & Zonen so much better than those from the competition?
The CGR 4 differs from all other Pyrgeometers in that it allows accurate daytime measurements on sunny days without the need for a shading device. Due to the unique construction of the CGR 4, solar radiation of up to 1000 W/m² induces window heating of less than 4 W/m² in the overall calculated downward radiation. In the Baseline Surface Radiation Network (BSRN) manual (WMO/TD-No.897) an extended formula is described. This formula corrects for window heating and so called solar radiation leakage. Due to the very low window heating offset and optimal spectral cut-on wavelength, these corrections are not necessaire for the CGR 4.
What is the calibration interval of a pyrgeometer?
We advise to re-calibrate the Pyrgeometer every two years. More information about our calibration service can be found here:
I am using a Ventilation unit on the Pyrgeometer. Do I need to put this on 5W or 10W?
If the CVF 3 is used for a Pyrgeometer the effect of sunrise is not valid and continuous 5 Watt is preferred. In extreme cold climates , polar / mountain tops, the 10 Watt heater can be used continuously.