Wet Bulb Temperature Calculator
Calculated Wet Bulb Temperature:
Understanding Wet Bulb Temperature
The Wet Bulb Temperature (WBT) is a critical metric that combines air temperature and humidity to reflect how effectively the human body can cool itself through sweat evaporation. Unlike the standard "dry bulb" temperature you see on a thermometer, WBT accounts for the moisture in the air, which directly impacts evaporative cooling.
Why is Wet Bulb Temperature Important?
For humans and many other mammals, sweating is the primary mechanism for cooling down. When the air is very humid, sweat evaporates more slowly, making it harder for the body to dissipate heat. A high WBT indicates conditions where the body struggles to cool itself, leading to heat stress, heat exhaustion, and potentially life-threatening heatstroke.
- Human Health: WBT is a key indicator for assessing heat stress risk, especially during heatwaves. A WBT of 35°C (95°F) is considered the theoretical limit for human survival for extended periods, as the body can no longer cool itself even with maximum sweating.
- Occupational Safety: Industries with outdoor workers or those in hot environments (e.g., construction, agriculture, manufacturing) use WBT to establish safe work limits and prevent heat-related illnesses.
- Climate Change: As global temperatures rise, the frequency and intensity of extreme heat events, including dangerously high WBT conditions, are increasing, posing significant challenges to public health and infrastructure.
How it's Measured and Calculated
Traditionally, WBT is measured using a psychrometer, which consists of two thermometers: one measuring the dry bulb temperature and another with its bulb wrapped in a wet cloth (the "wet bulb"). As water evaporates from the cloth, it cools the wet bulb thermometer. The difference between the dry and wet bulb readings, along with the dry bulb temperature, can be used to determine relative humidity and, subsequently, the wet bulb temperature.
This calculator uses an empirical formula (Stull, 2011) that approximates the wet bulb temperature based on the dry bulb temperature and relative humidity. While not as precise as direct psychrometric measurements, it provides a very good estimate for practical purposes.
Example Scenario:
Imagine a summer day with a Dry Bulb Temperature of 30°C (86°F) and a Relative Humidity of 70%. Using this calculator, the Wet Bulb Temperature would be approximately 25.60°C (78.08°F). While the air temperature is 30°C, the high humidity makes it feel much hotter and significantly impairs the body's ability to cool itself, indicating a moderate to high risk of heat stress.