Psychrometer

An instrument used to measure the water vapor content of the air. It consists of two thermometers (dry bulb and wet bulb). After whirling the instrument, the dew point and relative humidity can be obtained with the aid of tables.

Psychrometer An instrument used for measuring the water vapor content of the atmosphere; a type of hygrometer. It consists of two thermometers, one of which (the dry bulb) is an ordinary glass thermometer, while the other (wet bulb) has its bulb covered with a jacket of clean muslin which is saturated with distilled water prior to an observation. When the bulbs are suitably ventilated, they indicate the thermodynamic wet- and dry-bulb temperatures of the atmosphere. One variety is the Assman psychrometer (a special form of aspiration psychrometer for which the ventilation is provided by a suction fan).

An instrument for measuring relative humidity by means of wet and dry-bulb temperatures.

An instrument used to measure the water vapor content of the air; a hygrometer consisting essentially of two similar thermometers with the bulb of one being kept wet so that the cooling that results from evaporation makes it register a lower temperature than the dry one and with the difference between the readings constituting a measure of the dryness of the atmosphere