Wet-bulb temperature (WBT) is the temperature read by a thermometer covered in water-soaked cloth, such as a wet-bulb thermometer
. It is a measure of heat-stress conditions on humans and is used to indicate the cooling effect of evaporation
. The wet-bulb temperature is always lower than the dry-bulb temperature, but they become equal at 100% relative humidity
. Some key points about wet-bulb temperature include:
- It is a measure of the heat content of the air, and the temperature is usually given in degrees Celsius
- The human body relies on the evaporation of sweat to cool itself, but in extreme heat and high humidity, sweat doesn't evaporate effectively, leading to increased body temperature, heat exhaustion, and potentially fatal heatstroke
- A wet-bulb temperature of around 35°C (95°F) is considered dangerous for humans, and at this temperature, people can only survive for a few hours
- Wet-bulb temperature can be measured using a thermometer with the bulb wrapped in wet muslin, which indicates the temperature of adiabatic saturation
Wet-bulb temperature is an important factor in heat stress prevention guidelines and is used by various agencies, such as the National Weather Service (NWS), to estimate the effect of temperature, relative humidity, wind speed, and solar radiation on humans
