Wet Bulb Dry Bulb Humidity

Wet bulb temperature t wb can be measured with a standard thermometer with some wet clothing cotton or similar around the bulb.

Wet bulb dry bulb humidity. The depression in wet bulb temperature allows the humidity to be calculated. The difference between these two temperatures is a measure of the humidity of the air. The wet bulb temperature wbt is the temperature read by a thermometer covered in water soaked cloth wet bulb thermometer over which air is passed. The dry bulb temperature is the ambient temperature.

The higher the difference in these temperatures the lower is the humidity. Dry bulb temperature t db can be measured with a simple thermometer as shown above. It includes a dry bulb thermometer a wet bulb thermometer and a psychrometric chart a graph that plots the relationships between the dry and wet bulb temperature relative humidity and dew point at constant pressure. By definition wet bulb temperature is the lowest temperature a portion of air can acquire by evaporative cooling only.

Note that continuously air flow around the thermometer is important to evaporate. At 100 relative humidity the wet bulb temperature is equal to the air temperature dry bulb temperature. When the psychrometer is swung around by its attached chain or handle the air causes the water on the wick to evaporate which. Since evaporation takes up heat the thermometer will cool to a lower temperature than a thermometer with a dry bulb at the same time and place.

Air humidity can be estimated by measuring. Given the wet bulb temperature dry bulb temperature and ambient pressure the humidity of the air can be calculated as follows. A wet cloth is placed over the bulb of a thermometer and then air is blown over the cloth causing the water to evaporate.