Do you know the working principle of wet and dry bulb?

Psychrometer is composed of two specifications identical thermometer, a known as dry bulb thermometer, the bubble is exposed to air, temperature measure ambient temperature. Dry wet bulb is composed of two specifications identical thermometer, a known as dry bulb thermometer, the bubble is exposed to air, temperature measure ambient temperature; Another called wet bulb, with special gauze soaked up the temperature, humid and try to keep the gauze, gauze moisture evaporate into the surrounding air and take away heat, make wet bulb temperature drops. Related to ambient air moisture evaporation rate, the lower the humidity of the air, the faster the evaporation rate, lead to lower wet bulb temperature. Visible, air humidity and there is a certain functional relation between wet and dry bulb temperature difference. Psychrometer is the use of this principle, by measuring the dry bulb temperature and wet bulb temperature to determine the humidity of the air.