Wet Bulb Calculator
Estimate the wet-bulb temperature from temperature and humidity.
Wet-bulb temperature reflects how much evaporative cooling is possible — key for heat safety.
How the Math Works
The Wet Bulb Calculator uses Stull's empirical approximation, a simplified formula that estimates wet-bulb temperature from air temperature and relative humidity without requiring complex iterative calculations. The method combines these inputs through a series of arctangent functions and square roots, balancing computational efficiency with reasonable accuracy for most practical applications. While exact thermodynamics involve psychrometric equations, this approximation provides a close estimate by weighting temperature and humidity contributions mathematically, making it suitable for quick estimations in engineering and environmental contexts.
Practical Applications
To apply this calculation, users input the current air temperature (in degrees Celsius or Fahrenheit) and relative humidity percentage. The calculator processes these values through Stull's formula to output the wet-bulb temperature, which represents the lowest temperature achievable through evaporative cooling. This is particularly valuable in HVAC system design, agricultural planning for irrigation needs, and medical settings assessing heat stress risk. For example, engineers might use it to size cooling systems, while farmers could determine optimal watering schedules based on evaporative cooling potential.
Day-to-Day Use
In daily life, this calculation helps individuals make informed decisions about outdoor activities, exercise routines, and personal comfort. When temperatures and humidity combine to produce a high wet-bulb temperature, it indicates dangerous heat conditions where sweat evaporation becomes inefficient, increasing dehydration and heat exhaustion risks. The calculator aids in planning sports events, gardening tasks, or even choosing appropriate clothing. Additionally, it enhances understanding of weather forecasts by translating technical data into relatable thermal comfort indicators, helping users prepare for extreme heat events more effectively.
Worked example
30 °C at 50% RH → about 22 °C wet-bulb.
FAQ
Why is wet-bulb dangerous?
A wet-bulb above ~35 °C exceeds the body's ability to cool by sweating.