Dry Bulb Wet Bulb Humidity Chart Celsius

The wet bulb temperature is always lower than the dry bulb temperature but will be identical with 100 relative humidity the air is at the saturation line.

Dry bulb wet bulb humidity chart celsius. Example the state of air in the psychrometric chart. Relative humidity is measured using a device called a sling psychrometer this consists of 2 side by side conventional thermometers one of which the wet bulb thermometer has a wetted wick placed at the bottom the other the dry bulb thermometer has no wetted wick. 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. Relative humidity temperature in.

These can be calculated automatically using wildland fire rh calculator apps for ios and android available for free. The following tables calculate dew point and relative humidity based on the observed wet bulb and dry bulb temperatures and the elevation at the site of the observation. Properties of atmospheric air such as the dry bulb temperature the wet bulb temperature the dew point temperature the specific humidity the relative humidity specific enthalpy and specific volume are discussed in relation to the psychrometric chart below. At lower humidity the wet bulb temperature is lower than dry bulb temperature because of evaporative cooling.

The relative humidity is approximately 50 the humidity ratio is approximately 65 grains h2o lb dry air. The dry bulb wet bulb and dew point temperatures are important to determine the state of humid air. Combining the dry bulb and wet bulb temperature in a psychrometric diagram or mollier chart gives the state of the humid air. The knowledge of only two of these values is enough to determine the state of the moist air including the content of water vapor and the sensible and latent energy enthalpy in the air.

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. Two independent intensive properties are required to completely specify the state of air in the psychrometric chart. The depression in wet bulb temperature allows the humidity to be calculated.

The state of air with dry bulb temperature 75 o f and wet bulb temperature 62 5 o f can be visualized in the psychrometric chart as indicated below. At 100 relative humidity the wet bulb temperature is equal to the air temperature dry bulb temperature.