Evaporation measurement, measuring evaporation using direct and indirect methods. Direct methods include all those in which a moistened sample body, such as a paper filter (Piche atmometer), porous ceramic discs (Ceratzki disc), or water bodies (evaporation vessels, evaporation kettles) are exposed to evaporation (evaporimeters). The evaporation height is determined by measuring the change in water height in the vessel, the required refill volume, or the weight loss. Evaporation vessels can be placed freely on the earth's surface, embedded in the ground, mounted on a measuring raft (raft evaporation kettle), or set up in a weather shelter or under a shelter. The aforementioned methods are very imprecise, since the water surfaces exposed to the evaporation process rarely correspond to the actual conditions on the land surface. Direct methods also include lysimeters. In particular, weighable lysimeters with high temporal resolution (measurement interval ≤10 min) allow the direct measurement of actual evaporation.
