Instrument by which the
relative humidity of the atmosphere may be determined. It is generally composed of two temperature
sensors, one of which measures the temperature of the air; the other sensor is moistened
with water and senses the cooling due to
evaporation of water. The temperature difference between the two sensors is a function of
relative humidity; sometimes referred to as a '
wet-and-dry bulb' thermometer.
Source:
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2196