What Is Wet-Bulb Temperature, and Why Is It Deadly?
What kills a person is not the heat itself; it is the moment sweat can no longer cool the body. For most people reading this, that moment feels far away. For millions of people, it has already arrived, and there is a way to measure it: wet-bulb temperature. Most of us have never heard the term "wet-bulb temperature" before, but we are going to hear it often from now on. Wet-bulb temperature is not just another weather number; it is a measure of what heat and humidity do to the body together. Do not confuse it with the "feels like" temperature; how hot something feels to a person depends on many different factors. This is a far more scientific concept. It takes its name from a thermometer wrapped in a wet cloth. A dry thermometer only tells you how hot the air is; a wet one also accounts for how much of that moisture the air can still hold. The body's cooling method is not some complicated mechanism; it is simply sweat evaporating from the skin. As sweat evaporat...