For example, a human can easily endure a 90 °C (198°F) sauna for 15 minutes. Whereas human skin will burn in just two seconds in just 65°C (150°F) water.
ELI5 please.
ELI5: Why does water burn skin at far lower temperatures than air does?
November 19, 2017
Related Articles
ELI5: The appeal of buying name products versus the generic …
ELI5: The appeal of buying name products versus the generic products at a cheaper price.
Sound* View Reddit by generalbrain_damage – View Source
shokalion
Because water is far more effective at transferring heat to you than air is.
It’s the same reason why if you put your hand in a 200C hot oven, it’ll feel hot but won’t burn you unless you hold it in there for quite a few seconds, but if you so much as brush one of the metal shelves you’ll get an instant burn. Everything in there, the air, and the shelves are all at 200C but air is terrible at transferring heat and metal is very good at it.
Another example is why at room temperature, a wooden spoon will feel warmer to you than a metal spoon in the same environment, because the metal pulls the heat *away* from you way more effectively. Your body interprets that as feeling colder, despite them logically being the same temperature to begin with.
Air being so bad at transferring heat is why you have to put thermal compound on the bottom of a computer processor cooler, to fill those microscopic air gaps with something that can transfer heat a lot more effectively.
HipToMyHop
Recently learned this in school. It has something to do with the heat capacities but let me explain the basics to you.
Air is a very poor conductor of heat, and molecules carry very less thermal energy compared to liquid. Plus, in air, the molecules aren’t as dense as they are in liquid so that means there’s less thermal energy in the same surface area (your skin).
So basically the molecules in water are denser, so they carry more thermal energy per surface area that they make contact with. Air can’t transfer the heat to your body as fast as the water.
showponies
Another interesting example of this is outer space, which is -270C (-455F). A lot of people think if you are exposed to the vacuum of space with no space suit you would instantly freeze because it is so “cold”. But this isn’t the case at all. Since space is a vacuum there is nothing for your body to conduct its heat into, so it is actually very difficult to cool down because you are limited to only what your body can radiate. This is actually a big challenge for engineers who work on satellites, the space station, and other space craft which need to be designed to effectively radiate waste heat so they don’t overheat and fail.
brazzy42
Water is much denser and also has a higher specific heat capacity.
Which means that at the same temperature, a given volume of water of water contains **3200 times as much heat energy** as the same volume of air.
With the little heat that air contains, the skin can deal with it by just absorbing it and having the blood disperse it through the body (which is mostly water and so its overall temperature will only rise very slowly), and by sweating, which absorbs a lot of heat through [evaporation cooling](https://en.m.wikipedia.org/wiki/Evaporative_cooler).
patefoisgras
The top comment did a good job explaining the question directly, but I’d like to expand on it.
The feeling of “hot” and “cold” do not reflect the nature of “high temperature” and “low temperature” respectively. Two objects at exactly the same temp can feel entirely differently (as you’ve come to notice in dry air vs. steam).
“Hot” is how quickly you are gaining heat, and vice versa, “cold” is how quickly you’re losing heat. Different materials transfer heat (to and from your body) at different rates; the same material transfers heat at different rates depending on the temperature difference.
kodack10
Ignore temperature for a moment and think about energy. Think about how much energy it takes to raise the temperature of the air inside an empty fish tank. Then think about how much energy it would take to raise the equivalent volume of water when the tank is full.
Water has a much higher heat capacity than air does. So there is far more energy in 65c of a gallon of water, than there is in 65c of a gallon of air.