Evaporation recorder is used to register evapotranspiration
The evaporation recorder according to Piche is a recording Piche evaporation meter. A 50cm2 filter paper disc serves as the evaporation body. A hose connection leads to the float vessel with float which is connected to a recording device for recording the evaporation level.
Water evaporates already at room temperature, provided the air is not saturated with water vapour, which would correspond to the dynamic equilibrium described above.
The principle of water evaporation is, for example, the basis for the open-air drying of laundry or the disappearance of puddles of water. The effect of evaporative cooling by water is the basis for the effect of thermoregulation by sweating, by extracting the heat of evaporation from the skin and thus cooling it.
In ecology, meteorology and climatology, a distinction is made between transpiration (sweating + leaf evaporation) and evaporation (evaporation of water on unvegetated / open land or water surfaces) as forms of evaporation, whereby both are also combined to form evapotranspiration.
The absorption of water into the earth's atmosphere through evaporation takes place on the earth's surface, e.g. water surfaces, soils and plants. Evaporation is mainly dependent on the following factors:
- Air temperature
- Air humidity
- Solar radiation (season)
- Wind strength or, to a certain extent, wind direction
- Surface conditions (soil type, etc.) and vegetation
- Water content of the soil or amount of precipitation.
The many parameters on which evaporation depends make it very difficult and time-consuming to determine. For this reason, evaporation is usually not measured, but only estimated with the help of mathematical models. The resulting evaporation per unit of time, i.e. the evaporation rate, so to speak, is called the evaporation rate.
A distinction is made between potential evaporation, which represents the evaporation rate that is possible in principle due to meteorological conditions, and actual evaporation, which includes the water content actually present, for example in the soil. The potential evaporation is always greater than or equal to the actual evaporation. In dry conditions, i.e. especially in arid climates, the two values can differ greatly.