Correct Answer - Option 2 : An open pan
Evaporation is a cooling process in which latent heat of vaporization must be provided by the water body. Vaporization rate increases due to faster winds but if the wind velocity is sufficient to remove all the vapor above the water surface, then any further increase in wind velocity will not affect the evaporation rate. Cetyl Alcohol is used to reduce the evaporation rate.
Evaporation is measured using an open pan. The most commonly used evaporation pan is Class A evaporation pan.
Class A evaporation pan is cylindrical in shape having 120.7 cm diameter and has a depth of 25 cm.
This pan rest on a carefully leveled, wooden base and is mostly enclosed by a metal fence to prevent animals drinking from it.
Instrument for measurement of evapotranspiration → Iysimeter
Instrument for measurement of capillary potential → Tensiometer
Instrument for measurement of humidity → Hygrometer
Instrument for measurement of radiation from sun → Pyranometer
Instrument for measurement of wind velocity → Anemometer