I used to always get confused as a kid when going swimming and the temperature gauge was around 20 degrees celsius but felt really cold considering the same temperature in air was warm. I still don’t really understand why this is?
In: Earth Science
Part of this also has to do with evaporation of water on your skin, which is always happening. So you get wet with cold water and you feel cold, but part of what makes it feel cold is that as the water evaporates off your skin the second you pull it out of the water, the evaporation process uses so much energy from you that it feels really cold. You can jump in freezing water and stay fully submerged and you can get used to that, but the second you step out of the water and the lightest of breezes helps speed us that evaporation process by moving the water-dense air from your skin and replaces it with drier air ready to suck up some more water from you, you feel that shit cold af
Temperature is to do with how much particles within a material are moving. Heat is a different thing. Heat is about how that energy flows. Veritasium has a few [videos](https://youtu.be/hNGJ0WHXMyE) about it. If you sit a book and a metal bar out in the sun, they’ll eventually reach the same temperature. But if you pick up the bar, it’ll feel hot. However, the book will (at most) feel warm. This is because metal is *really* good at transferring heat, but paper isn’t. So, the particles in the book and in the metal are vibrating equally quickly, but the particles in the metal are better at passing those vibrations on to your hand.
It’s the same with water vs air. In this case, you are warmer than them. But water is a lot better at sucking the heat out of you than air, which makes the water feel colder.
A wet suit works by holding on to water. Your body then heats up the water in the suit, and then this water doesn’t keep sucking heat from you. Without the suit, the water around you keeps changing for more, cool water so you keep losing heat. A blanket works in much the same way. You heat up the air under the blanket, and the blanket stops that air from being replaced by new, cool air.
Heat is a form of energy. Different material need different amount of heat to increase temperature. They also have different speed for transferring that energy to and from it.
When you feel something is “cold”, it’s because
1) The temperature is lower (seems obvious)
2) The matter is trying to equalize temperature by stealing yours
Energy try to equalize. It’s one of the rules of this universe. And if said universe had its say, everything would probably be as cold as the vacuum of space. But I digress, back on topic.
We now know why something feel cold. Now, why is it different for water or air? (or metal, or wood, or whatever) Well, remember what I said? Different material have different amount of heat required to change temperature AND speed for transferring it. (its due to density, which is another subject)
Now another piece of trivia: you cannot feel the temperature of something outside your body. What our body perceive as the temperature of the object outside is in fact the temperature of your skin in contact with the object. Your nerves are inside your body. Your body cannot get information that is outside.
So the whole thing is the following:
A colder material touch your skin. The heat leave your body to go into the material. Your nerves record the temperature available and send it to the brain. Brain decode information and tell you “you cold mate”.
Depending on the material, you will lose more or less heat at your point of contact at a given moment. Water draw heat faster and need more of it. So when you are in water, it steal your heat faster, and your body interpret that bigger loss of heat as a colder environment.
Different mediums have different abilities to transfer heat, some might transfer more while some might transfer less.
Water is denser than air and it draws heat away from the body 20 times faster than air. Water has a high specific heat which means it requires more energy to alter its temperature. If you are in the water and it’s below 98.6 (sorry American) degrees it’s going to draw energy away from your body in the form of heat. Same thing happens in air but like I said water will do it much faster.
Heat and temperature is not the same thing. Boiling water and steam are both 100 celsius, but steam has a LOT more heat energy. Likewise, water at 80 degrees and air at 80 degrees are both the same temperature, but the water has more heat energy. Water is denser and has a higher heat capacity, which means that it takes more energy to raise the temperature of water than it does for air.
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