5.5. Humidity measurement
For humidity measurements, capacitive humidity sensors are in common use. They are easy to use and of sufficient accuracy. They measure the effect of humidity on the dielectric constant of a polymer or metal oxide material. Advanced measurement devices provide calculation of absolute humidity (g m-3), dew point temperature (°C), etc., in addition to relative humidity (%). For outdoor measurements, the probe has to be kept in the shade. The sun will heat the internal temperature sensor, which leads to false calculation of relative humidity.
For application within honey bee colonies miniaturized sensor heads (with a diameter of a few mm; see Kovac et al., 2010; Stabentheiner et al., 2012) are of great advantage. The use within colonies requires protection of the probe from the bees. Otherwise they may cover it over with wax and propolis.