Humidity measurement

In addition to temperature, humidity, i.e., the water vapor content of the air, is a meteorologically important quantity. This becomes understandable when one considers that water in its various forms is involved in a large number of meteorological phenomena. This applies not only to clouds, fog, and the many types of precipitation, whose formation, as well as evaporation, also requires enormous amounts of energy, but also to the emission and absorption of long-wave radiation, for which the water vapor content of the air is essential.