Visibility measurement

The visibility is measured with a "Present Weather Sensor" (Biral SWS100) by scattering an infrared light signal. The detection of visibility is mainly used to detect the presence and density of fog. The maximum visibility captured is 2000 m. The SWS100 can also quantify precipitation and its type (rain, snow, etc.). This is used to characterize the weather according to WMO code 4680.