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Wet bulb: It's the heat and the humidity

Next time you find yourself in a conversation about extreme heat, try inserting the following line to mix things up: “Yeah, but have you heard about the wet bulb...

If the US military has been using wet bulb temperatures for decades to decide whether or not it’s safe to work outside, why hasn’t the system reached everyday use? One reason could be that wet bulb temperatures are generally lower than the air temperature and heat index—they may not sound as bad as what the high temperature is or what the heat index is, giving a perception that things aren’t quite as dire as they are. That and, well, it’s a trickier concept to master than simple temperature, or heat index, which is already…

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  Wet Bulb Calculator

Enter the current temperature and relative humidity. The calculator will evaluate and display the estimated wet bulb temperature at those conditions.

 Forget Heat Index. Wet Bulb Globe Temperature Is Where It’s At.

One of the most common terms we hear during the summer when discussing the weather is Heat Index. While the Heat Index can give you an idea of how dangerous the heat can be, there is another lesser known variable that may give a complete description, known as the Wet Bulb Globe Temperature.

 To Keep Clear of Heatstroke, Pay Attention to This Metric

As the wet-bulb temperature climbs, the body loses its ability to cool itself with sweat. Heat index approximates how the combination of heat and humidity feels and is calculated based on air temperature and relative humidity. Wet-bulb temperature is measured by wrapping the bulb of a thermometer in a water-soaked cloth and then passing air over it until the water evaporates.

 Understanding Wet-Bulb Temperature: The Risks of High Wet-Bulb Temperatures Explained

High wet-bulb temperatures can indicate significant health risks for humans, especially vulnerable people like children, the elderly, and those with heart conditions or other chronic illnesses. While a wet-bulb temperature of around 95 degrees Fahrenheit is the theoretical limit for human survival, more recent research indicates that in practice, a wet bulb temperature of 88 degrees Fahrenheit can be hazardous even for young, healthy people.

 Wet bulb globe temperature is the vital weather stat you’ve never heard of

With the planet warming, wet-bulb globe temperature is going to be an increasingly useful measurement. Wet-bulb globe temperature (WBGT) is essentially a more nuanced version of the heat index. It takes into account not just the temperature, but also the humidity, wind speed, sun angle, and solar radiation levels (heat index only encompasses temperature and humidity, and assumes you’ll be in the shade).

Articles of Interest

Wet Bulb Globe Temperature Monitoring

WBGT has been shown to provide an accurate measure of environmental heat stress.

What is wet-bulb temperature? And how hot is too hot?

The answer goes beyond the temperature you see on the thermometer. It’s also about humidity. Our research is designed to come up with the combination of the two, measured as “wet-bulb temperature.” Together, heat and humidity put people at greatly increased risk, and the combination gets dangerous at lower levels than scientists previously believed.

Why you need to worry about the ‘wet-bulb temperature’

Scientists think we need to pay attention to a measure of heat and humidity – and it’s edging closer to the limits of human survivability

Resources

Thermopedia

The wet-bulb temperature is the reading registered by a temperature sensor placed in a moist gas stream and covered with a wetted cloth or wick. This temperature is lower than that of the gas stream itself, and is the dynamic equilibrium value attained when the convective heat transfer to the sensor effectively equals the evaporative heat load associated with the moisture loss from the wetted surface.