Kipp&Zonen CGR 4 Pyrgeometers - Manual (Page 28)

7. Frequently asked questions
The most frequently asked questions are listed below. For an update refer to the Kipp & Zonen website at
www.kippzonen.com
- What are typical values for downward atmospheric long wave radiation?
- The values calculated with the formula given in chapter 2 show a very strange value. What could be
the reason?
- Check whether the (instrument) temperature (T
b
) is given in Kelvin.
- Check that the net radiation (U
emf
/S) is a negative value, if not, the signal wires are possibly
interchanged.
- Is the pyrgeometer sensitivity affected by the length of the signal cable?
- With longer cable lengths the impedance increases, however it does not affect the radiometer
sensitivity for the following reason. The impedance of the voltage measurement device is at east
10000 times more than the impedance of the pyrgeometer plus cable. Therefore the current that
goes through the readout cable is negligible and won’t generate an offset.However, the loading
may affect the temperature compensation circuit to some extent.
- What is the primary entry point for humidity?
- The drying cartridge seal and the silicon glue of the dome are not fully airtight.
Page 28 CGR 4 Manual