What is a wet bulb temperature?

The wet bulb temperature is the lowest air temperature measurement that is the result of evaporation cooling and can be considered as a temperature that wet skin can feel when exposed to moving air. It is usually measured either by a psychrometer or a glass bulb thermometer wrapped in a wet cloth. When the water evaporates from the fabric, it lowers the temperature measured on the thermometer, although the evaporation rate depends on the relative humidity level. The full equation used for its calculation using other measurements is complicated, but can be estimated by means of a dew point and a dry bulb temperature. One common use of this measurement is to determine the efficiency of evaporation coolers in dry areas.

In general, a thermometer or mercury glass is used to measure the wet bulb temperature in the locality. The psychrometer uses a thin layer of water applied to the thermometer bulb, which spins around in the air, and for a bulb of a mercury glass, it is usually wrapped in a damp fabric or muslin. When jThe wet parts are exposed to air, the water evaporates and the heat is pulled out of the thermometer, which reduces the recorded temperature. The lowest measurement from the evaporation cooling is the temperature of the wet bulb.

Since evaporation has a cooling effect, the temperature of the wet bulb will always be smaller or equal to the dry bulb temperature, which is the heat content of the air. The evaporation rate has an inverse relationship with the air saturation level, also known as the relative level of humidity. When the moisture is high, it can evaporate and cool the wet bulb less water, so the temperature of the wet bulb will not differ too much from the dry bulb. On the other hand, lower humidity means greater evaporation and cooling, so the wet temperature is much lower than dry. Both temperatures will be the same if the air is 100%saturated because it cannot evaporate.

one can calculate the temperature of the wet bulb without having the thermometer of the wet bulb using an equationthat combines additional measurements such as dry bulb temperatures, latent heat, barometric pressure and relative humidity. A simpler way to estimate only uses the temperature of the dry bulb and dew point. First, it is necessary to deduct the dew point from the dry temperature and divide this number by three. The number from this calculation is then deducted from the dry temperature.

Example of how wet bulb temperature is used in everyday life, can be seen in evaporation coolers, sometimes called swamp coolers, commonly used in dry places to cool the inside of buildings and houses. The cooler contains an absorption material that is moistened with water and the air is then thrown out with the material. The process adds moisture to the air, making it feel cooler. The evaporator coolers can generally reach 70-95% of the outer air of the wet bulb. Coolers do not create the same results in humid areas, because not so much water can evaporate, so they do not reduce internal temperatures by a significant amount.