What is Wet Bulb Temperature?
Wet Bulb Temperature (WBT) is the lowest temperature that can be reached by the evaporation of water only. It is a unique measurement that combines air temperature (dry bulb) and relative humidity. Unlike standard thermometer readings, the wet bulb temperature accounts for the cooling effect of evaporation, which is exactly how the human body cools itself through sweating.
When the humidity is high, water doesn't evaporate as easily. Therefore, the wet bulb temperature will be closer to the actual air temperature. In dry conditions, evaporation happens quickly, leading to a much lower wet bulb temperature. This measurement is critical for determining heat stress on the human body.
Why is Wet Bulb Temperature Important?
Scientists and health professionals use Wet Bulb Temperature to determine the "limit of human survivability." When the WBT reaches 35°C (95°F), the human body can no longer cool itself by sweating, even in the shade with unlimited water. Exposure to these conditions for more than a few hours can be fatal. Even at lower WBT levels (26°C to 32°C), physical labor becomes dangerous, and the risk of heatstroke increases significantly.
How to Use This Calculator
Using our professional Wet Bulb Temperature Calculator is simple:
- Enter the Temperature: Input the current dry-bulb temperature from a standard thermometer.
- Select Your Unit: Choose between Celsius or Fahrenheit.
- Enter Humidity: Provide the relative humidity percentage (found on most weather apps).
- Analyze Results: Click calculate to see the WBT. If the result exceeds 30°C, extreme caution is advised for outdoor activities.
Frequently Asked Questions
What is the difference between Dry Bulb and Wet Bulb?
Dry bulb temperature is what we usually refer to as "the temperature"—the heat of the ambient air. Wet bulb temperature is measured by covering a thermometer bulb with a wet cloth; it reflects how much cooling can occur through evaporation.
Which formula is used here?
This calculator uses Stull’s formula, which is one of the most accurate empirical formulas for calculating wet bulb temperature from air temperature and relative humidity at standard sea-level pressure.
What is a dangerous Wet Bulb Temperature?
A wet bulb temperature above 27°C (80°F) is considered cautious for strenuous activity. Anything above 32°C (90°F) is considered extremely dangerous, and 35°C is the theoretical limit of human tolerance.