EVAPORATION PAN

An open tank used to contain water for measuring the amount of evaporation. The U.S. Department of Commerce Weather Bureau Class A pan is 4 feet in diameter, 10 inches deep, set up on a timber grillage so that the top rim is about 16 inches from the ground. The water level in the pan during the course of observation is maintained between 2 and 3 inches below the rim.