home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The Epic Interactive Encyclopedia 1998
/
Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
/
H
/
Hygrometer
/
INFOTEXT
< prev
Wrap
Text File
|
1992-09-02
|
805b
|
20 lines
In physics, any instrument for measuring the
humidity, or water vapour content, of a gas
(usually air). A wet and dry bulb hygrometer
consists of two vertical thermometers, with
one of the bulbs covered in absorbent cloth
dipped into water. As the water evaporates,
the bulb cools producing a temperature
difference between the two thermometers. The
amount of evaporation, and hence cooling of
the wet bulb, depends on the relative
humidity of the air. Other hygrometers work
on the basis of a length of natural fibre,
such as hair or a fine strand of gut,
changing with variations in humidity. In a
dew-point hygrometer, a polished metal mirror
gradually cools until a fine mist of water
(dew) forms on it. This gives a measure of
the dew point, from which the air's relative
humidity can be calculated.