An electrical ventilation psychrometer based on suggestions by the WMO

An electrical ventilation psychrometer, which deviates in some details, has been designed, built and tested in the laboratory and in the field. Owing to the international character of the instrument, a detailed report is given about the design and the tests. The psychrometer will mainly be used in automatic remote-transmitting meteorological stations; it can, however, also be used for other purposes of humidity measurement. It is equipped with Pt-100-resistance thermometers which are exactly adjusted to the normal values according to TGL 0-43760 plus 5 ohms, and therefore, subsequent corrections are not necessary.