Answer:
A psychrometer is a simple type of hygrometer. A hygrometer is an instrument which is used for measuring the humidity in an environment.
A psychrometer is a device which uses the difference in readings between a wet-bulb thermometer a dry bulb for measuring the relative humidity.
The bulb that is wet will cool by evaporation to the "dew point". Comparing this wet bulb to the dry bulb (the general air temperature) on a comparative chart will yield the approximate relative humidity.
