(didnt know the right flair)
I am european so i write in celcius!
I am curious how we perceive temperatures (if thats the correct way of putting this).
We have given temperature a standard number for us to make is easy to name it. So 37 degrees (bodytemperature) is for everyone the same.
But how does it work when we give it the names “hot” and “cold”? for example: When you want to take a bath 37 degrees is the minimun temperature for it to be nice, maybe a little higher for your liking, but whenever the news will announce that the temparature outside wil be 37 degrees the next week, we will call it hot. 24 degrees wether is nice wether, but 24 degrees water for a bath is cold.
But its the percieving side of it that i dont get. How is that so different for different surroundings?
In: Other
As part of living the body produces heat. This heat needs to be shed into the surrounding environment. The rate heat transfers varies based on the difference between the temperatures. But not all environments convey heat at the same speed.
Water is about 23.5 times better at transferring heat from the body than air. This means that if your body needs to dump a certain quantity of heat it will be able to do so when water is closer to the temperature of your body, than it would if air was that close to body temperature. Air would need a greater temperature differential to boost the speed heat transfers in order to match that of water.
That explains why water and air are different at similar temperatures, but how temperature *feels* is another huge topic. Something to understand is that the nerves that sense temperature are within the flesh of our bodies so they don’t directly sense the temperature of the things we touch. Instead they allow our brain to deduce the temperatures of things we touch based on the rate of temperature change within our flesh. Remember that the rate of temperature conduction increases as the difference in temperature increases, so when the nerves detect a higher rate of change in temperature within our flesh our brain tends to assume this is because of a greater temperature differential.
However there are other reasons that can happen. Metals for example can conduct heat more readily than other common materials, so when we touch a metal surface at room temperature it can convey heat away from our body faster than for example wood. Our brain though will tend to interpret this increased speed of temperature loss to the material actually being colder, which is why metals tend to “feel cold” even though they are actually the same temperature as everything else nearby.
Beyond that our bodies tend to adapt to ambient conditions such that if you become used to being outside during a cold day, coming inside the air will feel very warm even though later once you become acclimated it feels normal. Add all those factors together and how temperature subjectively feels is very complex and unlikely to be objectively accurate to the real temperature.
The main way that people cool off is by sweating.
When you’re already surrounded by water sweat won’t be able to cool you off so you’ll feel hotter.
It’s the same reason that humid days feel hotter and cause more people to have heat stroke than non humid days with the same temperature.
when the ambient temperature is higher than your surface temperature, you feel hot
when the ambient temperature is lower than your surface temperature, you feel cold
of course there’s more than that, but it’s the gist of it
things like humidity, wether you’re directly in the sunlight or not, and how fast is the wind moving affect the temperature that you feel
How you feel when in contact with something, that includes air. is not directly proportional to its temperature. What is relevant is how fast it transfers heat to and from you. I disagree water need to be 37 C to be nice, I prefer cooler water.
A typical hair dryer output air at around 70C and it is warm when you start to blow it on your skin. Compare it to water at 70C which will scold you. The difference is that water contains more thermal energy and transfer it to you at a higher rate. Another example is an oven where the air is over 200C and feeling hot bull will not damage you immediately, compare that to touching hot metal in an oven that have the same temperature and you get immediate burn damage. The metal heats you up faster.
Over time air can heat you up so if you were in a room at 70C for a long enough time it would increase your body temperature and you would die. For a short duration, a hot room like that can be nice and we call them saunas. A room is different from the outside air temperature because you can not escape the outside air as easily. e A sauna is nice for a couple of minutes the you go outside and cool down. A warm bath is nice to because you can easily get away. You can’t get away from the hot outside air unless you go inside to a air-conditioned or otherwise cool indoor space.
Your body produces a lot of heat and it needs to be removed. If you are in a medium that is 37C you can get rid of it without sweating and water evaporating. That will not happen in a pool, so saying to long in water that warm will result in you internal body temperature rising higher and it can be dangerous.
There is another factor, how is temperature measured? In the water is is just the water temperature, that is easy.
But air temperature is just the temperature of the air measured in shade, when you are outdoors you are often in sunlight and that will heat you up. It is not included in the air temperature measurement. Compare how if feels on the shaded side of a house compared to the side in direct sunlight and you will notice the difference in the sun.
Hot and cold is alos what is expected, if your food is too cold it can still be warmer than what you consider a warm day, It is just cooler the you like it to be. For some drinks we prefer them to be below body temperature and others above so a warm beer can be room temperature exactly the same temperature as cold coffee
Latest Answers