Great question, although it’s a strange name I would argue that if you’ve ever had anyone say to you “don’t worry, it’s a dry heat” you already fundamentally understand what wet bulb globe temperature is measuring. Namely, the humidity plays a huge role in what temperature feels like. We all know there’s a big difference in how bad it feels between 90 degrees Fahrenheit with 20% humidity versus 90 degrees Fahrenheit with 70% humidity.
The term wet bulb temperature dates back to the 19050s when scientists were looking for a way to measure this combined effect of heat and humidity. At first they did this just by reading the temperature from a thermometer whose bulb had been wrapped in a wet towel. But as technology advanced, a device like this was developed that added the globe part to wet bulb globe temperature. This globe was black to better absorb sunlight and had taken into account the effect of solar radiation along with humidity.
Today, wet bulb globe temperature can be approximated using a series of equations and other measurements that don’t require this device. Wet bulb globe temperature is an important measurement because it takes into account all the things that we as people experience when we’re outside. At high wet bulb globe temperatures, it’s not even possible to be outside for long, if at all. For example, a wet bulb globe temperature of 90 degrees is roughly equivalent to a dry heat of 130 degrees Fahrenheit.
So even though wet bulb globe temperature may have a strange name, it’s very important to keep in mind when thinking about changing climates in the future.