Should You Wipe Off Your Sweat?
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- čas přidán 19. 12. 2023
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If you’re in scorching heat, or when your body is working hard and you’ve got hot, hot sweat all over, sticky and stifling - does wiping off the sweat help you cool off? Or is it better to leave it on?
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REFERENCES
Hyperphysics:
hyperphysics.phy-astr.gsu.edu/...
Engineering Toolbox Mollier Diagram:
www.engineeringtoolbox.com/psy...
Sweat Info
www.anaesthesiamcq.com/FluidBo...
Other articles:
www.slate.com/articles/health_...
onlinelibrary.wiley.com/doi/10...
lifehacker.com/5921036/dont-wi...
www.realclearscience.com/2012/...
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CALCULATIONS
Typical adult human body surface area ~ 1.5-2 m^2
en.wikipedia.org/wiki/Body_su...
Evaporation rate at 25°C and 50% humidity, slight air movement (v~.5m/s) = .35kg/m^2/hr
www.engineeringtoolbox.com/eva...
So in these conditions, a sweat-covered human can expect to evaporate ~.5-.75 L of water in an hour (For higher humidity (60-70%) it goes to ~.37-.5 L of water/hr). That amounts to ~0.25-0.35mm of sweat (covering the whole body) evaporated in an hour, or 6 micrometers every minute.
Water has latent heat of 2,270 kJ/kg (www.engineeringtoolbox.com/wat..., so in an hour a human can lose ~1100-1700 kJ of energy. (2270/4.1868 ~ 542 Cal)
BUT that assumes all of the energy came from the person. If some proportion of it came from the air (~1/3-1/2?) then the person is only cooled down partially.
Mass of a human ~ 60-80kg (en.wikipedia.org/wiki/Body_we..., assuming ~specific heat of water, ie 4 kJ/kg/K, could decrease temp by ~4.5-5°C.
Energy used in moderate-hard exercise is ~20-30 kJ/kg/30 min, or ~40-60kJ/kg/h (www.weightloss.com.au/weight-l.... Let’s say 50kJ/kg/h, which for average human amounts to 3000-4000 kJ/hr
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@@DontReadMyProfilePicture.57 Don't delete your youtube account
@@DontReadMyProfilePicture.57 ok I won't
@@DontReadMyProfilePicture.57 Thats the best CZcams advertising I've ever seen ... but lots of effort for an almost empty channel.
so you are talking calories or kilocalories ? why do people always...yes always get that incorrect. I drive 2 kilometers to work, not 2 meters
@@whyranooooo Depends how smooth your brane is.
This is why I avoid any room with more than 2 physicists.
Physicist have also proven that fist- or elbow-bumps are better than handshakes, because their hands are gross, man
Are you “breaking cold sweat”?😰
I wonder if you yourself are a physicist
Two physicist is already too much for normal person to handle
Sweaty, stinky physicists are the smartest!
And when you're done smearing it around yourself, you can smear your sweat on others to cool them down faster too!
PHYSICS
Not sure everyone else would be ok with that, but I guess from a physics perspective, it’s valid
Why waste your sweat on others? Why not smear your saliva on others to cool someone else?
@@aamirrazak3467 Whoosh.
Or you can steal it from others and smear it to yourself too
As a logger who works in the scorching heat of the southeast US, I can confirm that leaving the sweat on you is best. Trust me, I know by experience. If you need to wipe it away from your forehead to keep it out of your eyes, yeah go ahead. But leave the rest to evaporate and keep you cool. If your shirt gets drenched, it can be a tricky situation. Yeah, it'll evaporate, but it may hold heat under the wet shirt as well. Fanning the shirt to get air to flow through it is best in my opinion rather than taking it off. That gets air moving through it and it removes a lot of heat that way and when you stop and let it rest back against your skin it will feel much colder than before. Just some advice from a guy who's had bright green shirts go white from all the sweat that runs through them and a guy who cuts trees in the heat of the southeast for a living.
This makes me glad to live in the west. At least sweat evaporates fast here. You can sweat buckets without realizing it because the dry air just pulls the water right off your skin. It can cause dehydration if you aren't local and don't realize how it works here though.
Im greatful for your practical knowledge my guy
I guess loggers probably don't use wood chippers too much but standing in front of the radiator intake is better than AC when you're soaked in sweat
[Edit]
It will literally suck you dry in like 5 seconds. The cooling power from that much water evaporating off your skin can seriously give you the chills when it's 95°F outside.
The idea is you jump in beside the chipper for 30 seconds before lunch, instead of getting in the AC truck all sweaty
@@amosbackstrom5366 standing in front of an AC outlet is 100x better.
I think I've read that fishnet underwear is supposed to be good for wicking away sweat and keeping an air gap between your clothes so they don't get soaked. No idea if they work though.
This is why in cold conditions the best gear emphasises keeping you dry as much as keeping you warm. You want to manage your level of insulation to avoid sweating while active, a base layer that whicks the sweat away from your body before it evaporates, and breathability in your shell layer to keep it dry.
Also, wet clothes conduct heat a lot better than dry clothes, with wool being the notable exception
So what's the deal when going skiing : should we remove any sweat from under our clothes as soon as we get a bit too hot?
@@Max-px5ym As long as you don’t intend to do anything that would expose you to more cold, such as taking of your jacket, there should be no need to do that
Edit: I guess taking a break would also count as a cold exposing act
@@younscrafter7372 yes taking a break while sweating is the biggest danger in the snow, your core cools down while the sweat cools you down even more then if you had layered a bit less while moving.
I'm really happy you addressed the Pooling of sweat being less efficient at evaporating, but even happier you suggested smearing it all over rather than wiping, i laughed so hard at that XD
If your sweat is pooling on the cold hard floor, roll around in it, naked! The floor will act as a heat sink and the sweat that you just wasted will act like liquid thermal compound increasing your contact area with the floor.
@@toolbaggers And pretend like it's the most normal thing.
@@SaHaRaSquad "pretend"?
I do this unironically when washing my hands in hot weather. I just wipe cold tap water all over my forearms and then wipe one hand dry to open the door.
@@PipPanoma You mean you don't take off your shirt and rinse it under the tap water before using it as a towel for your entire upper body, only to rinse it again before putting it on? Wow, you are a wierdo.
After doing lots of exercise in both hot, dry conditions and hot, humid conditions, my speculation would be that if you feel very sweaty over the exposed parts of your body, that's a sign that it already isn't evaporating well. In dry conditions I'll notice that, say, my back is very sweaty underneath a backpack, or other enclosed areas like feet and armpits, but my arms, face, etc. rarely get so sweaty I want to wipe if off, because the sweat is evaporating. In humid conditions, everything feels very wet, and it will typically stay that way even after I stop exerting myself and sit in the shade, which leads me to think it's mostly just sitting there and not evaporating. I also suspect that smearing it around wouldn't accomplish much, since the limiting factor is humidity in the air.
As someone who has lived in humid climates most of his life, I believe this is true the vast majority of the time. If you're feeling like you want to wipe it off, it's likely because you have way more than is necessary to provide cooling.
Yup. This is why in humid climates you carry a towel not to wipe it off but to sop up the excess with blotting and not wiping. Evaporative cooling works infinitely better when surface tension isn't a significant part of the equation.@@robgronotte1
@@miinyooI noticed this when I moved from Canada to Japan. It was the first time seeing so many people carry towels around their necks while hiking.
I also think that it’s really hard to wipe completely dry when you’re already hot and sweating. So simply wiping to remove that top layer of sweat seems to vastly improve cooling.
My personal preferred method is to use a wet cloth to replace the sweat with regular water rather than drying it off, assuming I have access to one. Aside from the obvious benefit which is that cold water is colder than hot sweat, it also has more surface area to evaporate quickly since it beads up less, and it still helps somewhat if sweat is collecting too much on your face and also doesn't feel nearly as gross to leave on.
At some point the sweat will become so concentrated with salts that evaporation nearly ceases so wiping that mess off would make sense. I have done much roofing in hot, humid weather and I usually have to change my shirt at some point because it becomes like sea-water and never dries (not to mention the odor).
I mean no one told you to not take a shower!!!
I think I've read that fishnet undershirts are good for this but I don't have any practical experience.
@@himanbam to accumulate salt crystals? First I would use a hose in a break to freshen up if possible wash the face possibly torso, second I sweated a lot and never reached such a point that "evaporation nearly ceases"
@@Freakhealer You get how it's easier to keep a spare shirt in a bag at a worksite than it is to take a damned shower while out at a roofing job, right?
I've always been anti-wipe, glad it applies to sweat too
I don't think that's going to evaporate.
@@rafflesmaos It also doubles as a r*pe deterrent
Physics just got grosser.
@@toolbaggersno, it just filters dirtier **pists in
@@rafflesmaosIt's an emergency snack
As someone who's dealt with severe sweating issues my whole life, I found this video to be informative.
The best video to release during the winter ❄️❄️
it's not winter everywhere. Half the planet is summer.
@@sam3317
I know
It's a joke
relax
Build a snowman, Idk
@@norudeRelax, it's just an observational comment.
@@sam3317nope, the area between the tropics doesn't have summer OR winter seasons. Which actually makes it *worse* for OP, because as it's not a 50:50 split the majority of the world is not in summer.
Ten years ago I designed an electric race car, and as the car was used for longer and longer races the electric motors would overheat. Taking physics into account, I designed an evaporative cooling system in which ice cold distilled water is sprayed over the windings of the electric motors when the motor temperature exceeds 105°C, and, depending on ambient temperature, the car uses 2 to 4 liters of water per hour to keep cool. The entire system (water jug, water, plumbing, pump, valves, wiring) added less than 5kg of weight to the car, far less than a conventional radiator cooling system would have weighed, and the evaporative cooling is more effective as well.
Most recently the car raced in the 25 Hours of Thunderhill, completing over 1500 miles in 25 hours, and used a little over 10 gallons of water in the process.
Goes to show that while electric motors are vastly more efficient they still have overheating issues, hence why some high performance EVs still use radiators not only to cool down the motors but keep the battery temp down low as well.
@@TheSilverShadow17 you are correct, and energy is energy so 99% efficient still means 1% waste heat, which has to be managed. I didn’t mean to suggest that evaporative cooling would work for street cars, just that it worked well for my race car.
@@jpe1 Precisely. Then we've got the 2nd law of thermodynamics which exists and is around every corner in the universe, because that alone is what's stopping anything from reaching total and for the lack of a better description 'true' efficiency. Hitting that magic 100% efficient mark is in the realm of imagination but I digress on the matter. That being said, It's nice to talk to someone who knows and properly addresses the issues firsthand about what goes on with electric cars. The design and execution can make or break the difference simply put.
@@jpe1 All things aside I give you props for making evaporative cooling work on your race car, because under normal circumstances EVs are absurdly heavy with additional tech packed onboard.
So I should also scoop up the sweat of others and spread it on my body?
Thanks for the tip! 👍
I regret being able to read.
Yes.
@@jasondoe2596 OP was cursed with the knowledge of writing and decided to make it everyone else's problem😅
Dude years ago i watched you every day. I found your channel again and im so happy i found it again :D you really are awesome
Better yet get the best of both worlds!
Take a bandana, wipe off the sweat, soak it in cold water, and wrap the bandana around your neck or forehead. This will:
1 remove warm sweat, taking heat with it
2 add colder water that will cause liquid cooling
3 the water in the bandana will evaporate, causing evaporative cooling
When the bandana gets warm and gross, you can literally Rinse and Repeat.
Except the effort or doing this likely creates even more waste heat
@@madhououinkyoma If you're already sweating bullets, I think the waste heat from that would be negligible
i was litterally thinking about this today morning, and you uploaded a video. wow
Generally, this makes sense. However, there is a a complication. Because of the surface tension, sweat beads up. And at a certain point the beads combine, which reduces surface area. Right before they all combine, there is a sweet spot where surface area of sweat is greater than when they all combine. Since evaporation is a function of surface area, it might make sense to wipe the sweat when the beads combine and let them rebead.
In my practical experience you are correct. Whatever the reason I feel cooler when wiping beaded sweat from my head. I think the act of wiping away excess sweat also serves to spread it out and break up the beads as you suggest. Maybe don't use a super absorbent material to wipe sweat though.
Sweat doesn't bead very much because you also secrete oils and minerals that break the surface tension somewhat. It smears out fairly well, especially if you're working hard and you're all gross and dirty.
I'm skeptical because I doubt that those droplets ever fully leave the skin dry. If so they actually increase the surface area (a dimpled surface has greater exposed surface area than a flat one). Your skin isn't like a hydrophobic waxed surface as on a car.
@@petergerdes1094 Beads of water are gigantic. It's much better to blot them with a towel and make them smaller especially in a very humid environment. If you suspect you've touched allergy inducing oils such as poison ivy, it's even more important to blot the excess sweat away and not wipe.
@@miinyoo That might be right but I'd like to see the calculation comparing the effect of increased surface area to increased thermal mass. Or better yet an actual experiment.
Yes, ofc if you can move them to a dry area that's a win but assuming everything is wet it's less clear.
This is why you feel so cold when you get out of the shower, but your hair doesn't feel cold despite being wet for a long time after (if you have long hair that is). It just isn't evaporating fast enough
I advocate swallowing ice to get the heat of fusion cooling benefit.
I like that you include all the calculations.
I absolutely enjoy watching Yu our videos! Every one of them is a breath of fresh air and thought.
People can get lots of cooling by taking a shower, especially important to fresh air after lots of sweating.
Huh. I thought this video was going in a different direction, that is examining whether convective heat transfer is more efficient than evaporative cooling. But great video either way, and I’m glad you’re posting again. ❤
Convective heat transfer only works when the air is cooler than your body, and evaporative cooling only works when the humidity is low enough. There is a cave where the temperature is over 100 degrees Fahrenheit and humidity is 100%, and it's deadly because liquid condenses in your lungs and slowly drowns you.
Keep in mind that wind chill matters for evaporation. Sweating indoors does indeed remove less than a liter every hour in no wind, but if you're biking or running it can be much much more intense.
Also: This is why fans make you colder. The electric motor inside actually heats up the room (a little). But since moving air makes evaportive cooling more effective **you** still get cooler from it.
@@TheMightyZwomThe airflow generated by the fan is also enough to counteract the heat being released by the electric motor as well since you obviously don't want that to overheat and potentially catch fire.
@@TheSilverShadow17 I don't think counteract is the right word here. The airflow does not stop the heat from being generated (as conteract might falsly imply) but it rather dissipates the heat and - as you wrote - prevents the motor from overheating, yes.
I had to work in my attic in crazy summer heat once. I was sweating like crazy and kept wiping it off. But then I had an idea! I stripped down to just my undies and instead of wiping off the sweat, I wiped it over my body. It was gross, but it kept me waaay cooler.
I love that the most effective way of dissipating heat from our body, using water, is the exact same method we find that is used in our body.
How amazingly and finely tuned has it all been set up!
This question bothered me since a young age and im so glad someone else very credible tackled talking about it
Thank you! I've spent too many sweaty, sweaty hours thinking about this.
Amazing video! A couple of notes!Evaporation rates are highly increased as the water increases temperature so the sweat evaporating from your body is significantly hotter than room temperature and as a result, evaporation rates should be much higher than water just sitting at room temperature. Also, in regards to wiping out sweat, A thick layer of sweat, particularly in very humid environments can lead to an increase of themal resistance which can lead to colder sweat towards the outside which reduces evaporation rates. Bottomline, wiping sweat to keep a thin layer of sweat that is evenly distributed is your best shot at cooling! 😅
As additional tip. wear something that lets in air but also can get soaked pretty well (can absorb moisture). This way you effectively increase your total surface area or your cooling-by-evaporation capacity.
Three videos in a month? I could get used to this! Thank you!
I think I know the answer before watching but I just gotta watch these very rare minutephysics videos. The highlight of my year.
Leaving sweat on will cool you off more unless it get's too thick of a layer, is my hypothesis
As a physician myself, I should confirm that it is correct, and is commonly taught in physiology textbooks that cover heat transfering. It should be noted though that when air humidity is too high or when temperature is above corporal levels sweating doesn't do much for losing temperature (although drying yourself also doesn't), as the physics is based in the droplets of sweat absorbing heat from your body as latent heat, changing to vapor, so if air is saturated with water that sweat won't evaporate ever, and if temperature is too high sweat will be absorbing heat from the environment, thus reducing its efficiency from absorbing body heat. We're not very good at losing heat as we are at producing it
I work out 5 days a week and kept wondering about this when I get really hot and sweaty. Nice to finally have an answer.
I was not expecting to hear smearing excess sweat all over my face as an optimal, let alone socially acceptable, cooling practice. I couldn't stop laughing that came out of nowhere. 😂
They're not saying it's socially acceptable
I mean, I've rubbed the condensation on bottled drinks to give myself some extra cooling when working in the heat, and that's when I don't want to waste the water by just pouring some on me or when we don't have a cold faucet to splash myself with.
Is it socially acceptable? I mean, it's a little weird. But when you're hot as hell, you don't give two shits.
If your sweat is pooling on the cold hard floor, roll around in it, naked! The floor will act as a heat sink and the sweat that you just wasted will act like liquid thermal compound increasing your contact area with the floor.
So is shirt on or shirt off cooler...? Tight shirt or looser button shirt...?
Look at you, too refined to dab pit-sweat on your face.
We need a Quantum physics mini course like the Special theory of Relativity course.
Great, great video I was always wondering why yoga classes they tell you not to wipe out sweat. Happy new year and best for 2024.
I genuinely appreciate this video. I always strive to be as energy-efficient as possible as a human being, because if I establish the habits now I can prolong my survival in the impending apocalypse.
Excellent advice.
I was once in such dry and hot weather, that I didn't even realise that I was sweating, because it would evaporate as fast as it came out of my skin.
I only realised that I was seating once I got inside where it was cooler, and my arms went from being bone-dry to slick-wet and almost dripping onto the floor.
I’ve enjoyed all three videos in December. I’m not upset that there was potentially video sponsor obligations to be met by the end of 2023 that prompted this burst of uploads!
thank you! very interesting and useful for min-max-ing life ;)
I just realized, its the comeback!
This is very interesting! Thanks for the Video!
It literally just came out u couldn’t have watched the whole thing yet u capper
He is back! :D
Great video!
Small note though, modern studies dismiss the 2m² skin surface theory since the skin isn't 'flat', and so the surface area is a bit more (not including the follicles of course since those play a minimal role when talking about heat evaporation).
Interesting. I've also read that an appreciable portion of body heat loss happens through the humidification of breathed air (evaporative cooling).
That means that in air at 100% relative humidity and 100°F (body temp), evaporative and convective cooling both completely stop, leading to imminent heat stroke within 2 hours regardless of physical activity or sunlight.
Even though this is not really related to sweat, I always found it interesting.
Nice video!
Love this
I used to push carts outside at Walmart. In the scorching hot sun, you need to wear sunscreen. But what happens to the sunscreen when you sweat? Well, your sweat mixes with the sunscreen, and if you take this advice and don't swipe that sweat, the ish burns like crazy if it gets in your eyes lol. Keep a cloth in your pocket designated for wiping sweat, or keep some fresh paper towels nearby to wipe the sweat off when it starts pouring down on your face.
Always suspected this question - to wipe or not. Thanks!
Thank you 😊
I like to put water on my face when I’m hot. I also like to wet my long sleeves when I’m working in the heat so my body cools better.
If my body is already dripping sweat doing nothing since it's that damn hot, there is no point in exercising more by trying to pick-up pooled sweat since my body would already have a layer of sweat all over. The best thing to do in this extreme heatwave example is to relax your mind and body and just to try to go to sleep in some shade to burn as little calories as possible.
Thank you.
If you're sweating so much the sweat is dripping, a sound medical advice is to wipe it off your face lest it drips down into your eye, blinding you momentarily and leading to a stupid accident like stubbing your toe, tripping on a curb or walking into a sign.
Don’t forget to speed up that evaporation with a simple, but crazy effective paper fan!
Getting stinging sweat in my eyes stops me from performing the activity that is making me overheat, which helps reduce my overall temperature. And then it's time for a refreshing cool drink. Win win win.
Please keep making videos
How much it helps if air is moving from a hairdryer (on a setting which doesn't heat up the air) or from a fan?
In practice smearing your sweat isn't optimal because in pretty much every circumstance that you've got excess sweat it will be in excess everywhere on your skin. Plus, it takes energy to do the smearing, generating more heat. These are the only two problems with this method though
I can't recall the situation I was in when I did this. But I can tell you that it helps
In my experience that's not always true. If you're naked and have a shaved head or in the most extreme heat maybe. However, I often find sweat will develop under in my hair and under clothing even while my exposed skin remains largely dry.
Let's promote the use of wet-bulb temperature over "heat index" when alerting people about heat danger!
Yes by litre evaporative is best and leave it there. But I have in the past come in from work and waiting for friends had a drink at the pub. My order is 2 schooners (425ml) of water first and then 1 of beer. Within 30 minutes I have had 3.4L of water and 1.7L of beer. (5.1L of 2deg Celsius of liquid) def works better then sweat, then I have calmed downed and ready for a drink. Before that on the work place though I will easily drink several liters per hour while working hard. My heavy cotton drill clothes get soaked then act as a Coolgardie Safe to keep me cool, 99% of my outside work life has been in a dry climate.
Thanks
This should be sponsored by a moisture wicking athletic fabric company. A fabric can significantly increase the available surface area of sweat for rapid evaporation and cooling.
smearing is best for cooling even if its not dripping. the droplet will evaporate faster. Although you may risk carrying off that sweat even if you try not to when smearing.
I've an idea for one of these efficiency questions.. No one likes flat soda or beer. When you pour soda/beer into a glass, it immediately foams from the agitation of pouring. If you pour it in fast enough, the head grows and covers the surface. It seems like the foam persists longer if you develop a head than if you pour slowly to let the foam dissipate as you pour. That is, if you pour slowly enough the head never forms a full layer. However, rumor has it that a foamy head will prevent carbonation loss. There are multiple factors involved, but how should you pour a drink to keep the most fizzy?
Honestly even if it is kind of gross you can shower afterwards and get the benefits of smearing sweat around while still being clean. Nobody is worried too much about how sweaty you are if its hot or youre working.
well us arabians wear a dishdasha and shmak for a reason its a loose fitting colthing with maximum air flow and covers from the sun and is usually white to reflect as much as possible +can keep you warm in winter if you layer with more clothing
I wonder if wiping sweat helps evaporation by thinning and breaking up the convective surface allowing improved evaporation. I suppose it would depend on if individual drops have better evaporation than a continuous sheet of sweat.
It takes heat to evaporate the sweat, but on a hot day it is being heated from the body and the surrounding temperature. If the surrounding temperature is above that of the body then we are mostly just extruding sweat (wipe it off). Below this evaporation is efficient down to a temperature too low for evaporation and we are just heating water outside our bodies (freezing sweat might have other issues).
I like to wipe my face with a wet towel instead
it spreads water around but isn't sticky like sweat
I hate sweating on my face because it always gets in my eyes or on the things I'm working with
Been watching this channel since as long as i can remember. Do you get free markers from Crayola?
if you smear it around, like you suggested at the end, wont you end up with a thin layer of sweat that's adhered to the surface of your skin and pores and make it slower to evaporate?
The answer is to the question I didn't have but wanted to know
Consider application of supplementary moisture via spray bottle instead.
do another "should you". I like the content
Some power plants use evaporative cooling. Nuclear plants with those Hyperboloid tower would be a (stereo)typical example.
The real calculation here should be comparing the extra surface area provided by a bead of sweat (effectively dimpling the water surface) to the extra mass over which that cooling is distributed. Other than that wiping doesn't affect it one way or the other (assuming someone/something else does the wiping for you so you don't burn energy)
I’ve always wondered this
Perfect video for late December.
Wait, what?
2:20 Marlon Brando's character in Apocalypse Now, rubbing his bald head in a way that only manages to smear around the sweat: *finally vindicated*
Get a small sweat towel to "smear" it around to a thickness that can be easily evaporated. Would have loved to hear something about the latent heat of vaporization.
From what ive heard drinking cold water will actually make your body produce more heat in order to heat it up to body temp leading to more sweating, hence why tea is so popular in arabic regions.
Not 100% on this so if anyone knows more feel free to let me know ;)
Good to know for survival situations
Glisten brightly, my friends.
You have skin oils too, which will film over your sweat beads and slow evaporation. It's okay to spread that sweat around or wipe it away from your eyes.
I remember working as a mover during a humid heat wave. We were moving a really heavy treadmill from and airconditioned basement. It was up a tight staircase and we were seriously exerting ourselves. The moment the heat hit us outside sweat started going in our eyes, rolling down our arms and off our hands. We had to put it down, from loss of grip. It was like someone dumped a bucket of water on us. To this day I've never experienced something like that.
But what about the chemical equilibrium of water within the body and outside? If the skin is the boundary regulating how much water is leaving the body through sweat, assuming it's semi-permeable, and havong sweat on the skin impedes further sweat from going through, then removing the sweat by wiping allows more sweat to leave the body?
When it's especially hot I actually find myself ADDING water to my limbs and face and neck region. Then I look to get some airflow going with an open door or window and a fan. It works wonders.
If your sweat is pooling on the cold hard floor, roll around in it, naked! The floor will act as a heat sink and the sweat that you just wasted will act like liquid thermal compound increasing your contact area with the floor.
Gonna start cooling my homemade pies by pouring water and running it through my pies from now on. I can't believe I never thought of that.
I work in the hills repairing wooden cabins sometimes. rubbing sweat round my neck and all exposed skin is a great way to cool quick. But I wouldn’t recommend for retail workers😅
Growing up in the northern stretches of the Ozark region, I never "got" how sweat was supposed to cool you off.
The issue with certain areas is that humidity can be _so high_ that the sweat just doesn't evaporate appreciably. Any amount of sweat hangs around for hours if not wiped off. (In other words, it is evaporating so slowly due to the humidity being so high that it just isn't functionally helping.)
Leaving the sweat on you is probably best, But I think also drinking water is fine as well
@minutephysics In your initial evaporative analysis, did you account for the fact that a person running will have air moving past them much more quickly, and therefore would have more evaporation? I assume human body skin temperature was already accounted for.
I might suggest using the abbreviation "cal" instead of "Cal" for ordinary calories (where 1 cal = 4.184 J), because by convention 1 Cal = 1 kcal = 1000 cal.
Greetings from Perth, Western Australia. One ot the ways I deal with a scorching Perth summer is to eat spicy food as the sweat generates cools you down particularly if there is a fan.
Can I ask why you didn't use joules for your units?
Now I wonder if sweat wicking clothing might be the most effective of all, drawing sweat away from the skin on to the surface of the garment, and also allowing it to spread out.
The problem with that is the evaporative cooling happens farther away from your skin, cooling down the air instead of your body. On top of that, the fabric insulates your skin, slowing down convective and radiative heat transfer with your surroundings. The cool shade of a tree will feel much less cool with a layer of wool in the way, for example.
@@areadenial2343 Not all sweat wicking clothing is all that insulating though, a lot of it is very thin and designed for high intensity activity.
@@areadenial2343 it cools down cloth itself which is in close contact with skin and air trapped in cloth, not air somewhere far. Insulation often good in hot weather, because environment hotter than your body. Cool shade is not cool and sun radiation heat you up way-way faster than you radiate back to environment.
But when you drink cold water, does that actually "cool" your body down like how a heat exchanger would work? I would think it's not just a direct correlation (ie assuming a person's body has a constant specific heat capacity), but a much more involved process of your body trying to maintain homeostasis. From what I've heard (and I don't know if this is true), your body needs to burn calories to heat up any cold food to body temperature as it is digesting. If you're burning calories, then wouldn't it mean that the water isn't being heated up (at least not completely) by the ambient heat? I mean, I'm sure a lot of people drink freezing cold water outside during the winter. In this case, you would also still maintain a relatively stable body temperature.
hmm yeah that's an interesting point, I'm curious now too. Hopefully someone knows how to explain this more but seems so complicated I'm not sure if there would even be reliable research on this. I'm not a biologist though so idk