A hygrograph is a meteorological measuring instrument for detecting and recording air humidity over a continuous period of time. It is therefore a recording hygrometer that controls a recording arm based on its specific input measurement method. This arm, in turn, has a writing tip at its tip, with which it transfers the air humidity or the corresponding humidity measurement onto a rotating paper drum, thus graphically displaying it. Hair hygrometers are the most commonly used input measurement method and display the relative humidity. The recording period is determined by the rotation speed of the paper drum. In weather stations, hygrographs are usually implemented together with a thermograph, which is subsequently referred to as a thermohygrograph.
