– what is a wet bulb temperature and why is it dangerous?
In: Biology
Wet bulb temperature is the temperature you read when your thermometer is covered in a wet rag.
Now you might be thing…why? Great question!
That’s because this allows us to measure humidity by comparing it to a “normal” thermometer that isn’t covered in a wet rag. Because the drier the air the lower the wet bulb will read, relative to the normal thermometer. That’s because the wet rag is actually like sweat! Sweat cools us off as it evaporates, and it evaporates faster the drier the air which means more cooling.
Not sure if you have ever heard the term “it’s not the heat it’s the humidity” or noticed that a hot day that’s muggy out feels *way* worse than a hot day that’s dry out but it’s the same principle here.
Not sure why you think it’s dangerous, though. It’s not. It’s just another way of measuring temperature. We do tend to talk about it when it’s both really hot AND really humid out, but that’s not because wet bulb temperature is dangerous. That’s because it’s really hot and muggy out.
The main way that we lose excess heat when it’s warm is by sweating. Warmer water molecules are released into the air as evapouration, leaving the less energetic ones as a liquid on the skin, allowing the body to be cooled. But air can only hold a certain amount of water in it. If it’s very humid, the water that evapourates from your sweat is immediately replaced by the water that’s already suspended in the air since it can’t hold any more water in it. When you have really warm and humid weather, the water that’s reintroduced into your sweat can even be warmer than your body, causing it to heat up beyond your regular tolerances.
The wet-bulb temperature measures this effect. You would wrap a thermometer in wet cloth and see whether it gets cooler or warmer, compared to the dry-bulb temperature. What’s the dry-bulb temperature, you may ask? That’s just what you measure if it’s not surrounded by wet cloth. In other words, the ambient temperature of the air. If the wet bulb is warmer than the dry bulb, people are in danger of overheating.
Wet-bulb temperature is measured by a thermometer covered with a wet cloth. Evaporation of the water reduces the temperature. Since air has a limited capacity to absorb water, the closer to 100% relative humidity it is, the less water evaporates, and the difference between wet-bulb and dry-bulb temperature is reduced.
Wet bulb temperature is a measure of temperature once as much water has been evaporated as possible as other said, the idea is that it simulate how sweat work.
The danger is when the wet bulb temperature is higher than the temperature of your skin, as it means you can’t cool yourself by sweating, and if you can’t do it another way, you will overheat and pass out, then die.
It’s not the heat, it’s the humidity that’s get you, as they say: as long as it is dry, you can sweat yourself cool as long as your sweat can evaporate
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