in mm of height of the water column evaporated. 2.6.2 Instruments to measure potential evaporation 2.6.21 Piche evaporimeter This evaporation gauge consists of a graduated glass tube which is closed on the upper side. To the lower, open side ab bdisc of blotting paper (usually cm diameter) is fixed with ab bclip. Filled with distilled water, the water loss from the paper surface is referred to the evaporative demand of the air. Although it is a cheap and a widely used instrument, the results are of rather limited value in water budget assessments. Hence it should be used only for special applications of a qualitative rather than quantitative nature.
