Psychrometers

Being a simplified hygrometer, the psychrometers measure the relative air humidity by comparing the readings of two temperatures. One temperature reading is taken exposed to the open air while the other is submerged in a liquid. The difference in temperature between the dry and wet bulbs, the psychrometer determines relative humidity when used in conjunction with a chart or slide rule. Advantages include the simple design of the instrument, economical savings, and portability.