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Built to be compatible with all standard National Weather Service evaporation measurements. This pan is normally installed on a wooden platform set on the ground in a grassy location. There are two commonly used procedures for making evaporation measurements. In both procedures a 10"D x 47-1/2"ID stainless steel pan is used to hold the water. The first procedure for measuring daily evaporation loss is to use a graduated hook gauge set on a still well to determine the level of the water's surface at each measurement. The second procedure is to use a still well with a fixed point, and each time a measurement is taken, refill the pan with a calibrated graduate having a surface area 1/100th that of the pan up to the level of the point. The amount of water added is the equivalent evaporation.
Since the amount of evaporation is a function of temperature, humidity, wind, and other conditions, in order to relate the evaporation to current or expected conditions, the maximum and minimum temperature of the water and the amount of air passage are normally recorded along with the evaporation. Submersible or floating type minimum and maximum thermometers are available for recording these temperatures.