Wet Bulb Dry Bulb Chart

Calculate the relative humidity.

Wet bulb dry bulb chart.

These can be calculated automatically using wildland fire rh calculator apps for ios and android available for free. 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. 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. Constant dry bulb temperatures appear as vertical lines in the psychrometric chart or horizontal lines in the mollier diagram.

Wet bulb temperature is lower than dry bulb temperature or equal to the dry bulb temperature. Barometric pressure 29 921 inches of mercury. 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 grainsh2o lbdry air relative humidity temperature in fahrenheit.

This equality occurs at only in air become saturated. Wet bulb temperature twb. By definition wet bulb temperature is the lowest temperaturea portion of air can acquire by evaporative cooling only. English imperial units with wet bulb and dry bulb temperature and relative humidity.

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. With enthalpy units in btu lb. Combining the dry bulb and wet bulb temperature in a psychrometric diagram or mollier chart gives the state of the humid air. At 100 relative humidity the wet bulb temperature is equal to the air temperature dry bulb temperature.

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 state of air with dry bulb temperature 75of and wet bulb temperature 62 5of can be visualized in the psychrometric chart as indicated below. Dry bulb temperature ranging 20 o f to 120 o f. The dry bulb temperature is an indicator of heat content and is shown along the bottom axis of the psychrometric chart or along the left side of the mollier diagram.