How are you when the weather gets really hot?

[[deleted user]]

I have noticed. :)

[Félix]

Lightning Googler.

[[deleted user]]

Larry, the fastest draw googler in the west.

[Lobstergirl, el principe]

Sally wrote: "Worhtless. I am worthless in the heat. I'd take the cold and a down parka any single day of the effing week."

Me too.

[Lobstergirl, el principe]

Alecia wrote: "My hoodies and sweatshirts don't come off till it hits at least 90 degrees. I have been accused of being cold blooded from time to time."

I sometimes see people like this and it freaks me out. Also, it makes me feel hot.

[Lobstergirl, el principe]

How hot is too hot for humans?


"Humidity makes us uncomfortable because we sweat in order to cool off, but this cooling is less efficient when it’s humid. Past a certain threshold of heat and humidity, our bodies can no longer cool off by sweating, and the results can be lethal. A recent study by Coffel et al. suggests that, by the end of the century, climate change may expose millions of people to life-threatening heat stress.


What is heat stress?

Heat stress is a term used to describe a range of heat-related illnesses, including heat exhaustion and heat stroke. Heat stress ensues when we lose our ability to thermoregulate, or maintain a steady body temperature. When our bodies overheat, biological processes get disrupted and this may result in death if left untreated. Heat stress occurs for a variety of reasons, including over-exertion, exposure to very hot conditions, and a reduction in our ability to cool off.

What might stop us from cooling off?

Humans cool off by sweating. When sweat evaporates from our skin, it changes phase from a liquid (water droplets) to a gas (water vapor). This phase change requires energy. Water molecules draw this energy from the environment, so the environment – in this case, our skin – loses energy and cools off.

Unfortunately, there’s a limit to how much water can evaporate. If the amount of water vapor in the air has already reached this limit, known as saturation, then it’s practically impossible for any more water to evaporate. Meteorologists use the concept of humidity to tell us how close the air is to saturation. For instance, if the humidity is 20%, then the air is pretty far from saturation; it’s dry, and more water can evaporate. However, if the humidity is 95%, then the air has nearly reached saturation; now it’s much harder for more water to evaporate. We can’t cool off as efficiently by sweating, which is why humid heat feels worse than dry heat!

Meteorologists have several strategies for quantifying the effect of humidity. You might’ve seen your local forecaster mention the heat index, which combines temperature and humidity in order to give you an idea of how hot it actually feels. A more scientific version of the heat index is a quantity known as the wet-bulb temperature, which essentially tells us how much sweat can cool us off, given the current air temperature and humidity. If the wet-bulb temperature exceeds the temperature of our skin – roughly 95 F – that means that sweating can’t cool us back down to a temperature that’s normal for human bodies. Our bodies heat up and illnesses such as heat stroke might ensue. Sustained exposure to such conditions is probably fatal, even for healthy people who aren’t doing any physical work.

To put this in context, a 2015 heat wave in India resulted in a wet-bulb temperature of 86 F. This is well below the 95 F threshold, but even so, the heat wave caused over 2,500 deaths (read more here). Fortunately, it is extremely rare for wet-bulb temperatures to exceed 85 or 86 F anywhere on the planet today. Unfortunately, a recent study suggests that this might change by the end of the century."


https://envirobites.org/2018/01/26/ho...