A Hook gauge evaporimeter is a precision instrument used to measure changes in water levels due to
evaporation. It is used
to precisely measure the level of a free water surface as an
evaporation pan or a tank. The main users are
meteorologist
A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while t ...
s and water engineers, especially in hot, arid countries where water conservation is of vital importance.
Description
The device consists of a sharp hook suspended from a
micrometer cylinder, with the body of the device having arms which rest on the rim of a
still well inside the pan. The still well serves to isolate the device from any ripples that might be present in the sample being measured, while allowing the water level to equalize. The measurement is taken by turning the knob to lower the hook through the surface of the water until
capillary action
Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...
causes a small depression to form around the tip of the hook. The knob is then turned slowly until the depression "pops," with the measurement showing on the micrometer scale.
Use
Evaporation rate is determined by a sequence of measurements over a set time interval, usually every 24 hours.
See also
*
Atmometer
An atmometer or evaporimeter is a scientific instrument used for measuring the rate of water evaporation from a wet surface to the atmosphere. Atmometers are mainly used by farmers and growers to measure evapotranspiration (ET) rates of crops at an ...
References
Measuring instruments
{{technology-stub
fr:Bac d'évaporation#Instrumentation connexe