Why do cold clothes feel wet?
July 30, 2008 5:14 PM   Subscribe

Why do cold clothes feel wet?

It's winter right now in Sydney, and cold. I put clothes on the line to dry, a day later I go out to collect what I assume are dry clothes, but they still feel wet, even though I know they are not (it hasn't rained on them, they are under cover, but still outside. I bring them inside and once they warm up to room temperature they feel properly dry.

What's going on here, in terms of physics etc?
posted by robotot to Science & Nature (14 answers total) 1 user marked this as a favorite
 
I think it's just that your body is losing heat pretty rapidly to the cold clothes and your brain interprets that rapid heat loss as 'wet'. When I first shaved my head, it felt wet for about two days until I got used to it.
posted by pombe at 5:24 PM on July 30, 2008


The body has no 'wet' sensors so it compensates by interpreting cold+pressure as wet. This is also why you think your raincoat is leaking if you're wearing short sleeves while it's raining outside - the cold pressure of the jacket on your arm makes you think your arm is wet when really it's dry.
posted by jpeacock at 5:33 PM on July 30, 2008


they've gone from insulating your body (air pockets) to conducting heat (water)
posted by zippy at 5:33 PM on July 30, 2008


Never mind, though the question was "why do wet clothes feel cold"
posted by zippy at 5:34 PM on July 30, 2008


My mother taught me to test for wet v. cold by touching the clothes to my cheek - I don't know how it works, but you can tell the difference somehow, more sensitive skin? More conscious attention to sensation?
posted by jacalata at 5:53 PM on July 30, 2008


two reasons:

first, water evaporates, which lowers the temperature relative to what it would be dry (that's because "evaporation" in physical terms is the loss of the fastest moving water molecules, which tend to fly off into the atmosphere, and "fast moving" means hot, so you're losing the hottest molecules, hence the temperature drops - wind chill is the same thing, except that the wind helps even more fly off)

second, water conducts heat better than dry cloth. so not only are the clothes colder than normal, they are better at conducting your body heat away from you than normal.
posted by not sure this is a good idea at 5:54 PM on July 30, 2008


oh crap, i've got it mixed up too. sorry.

i guess your brain is working backwards. it knows that wet clothes are colder (see above :o), so when it gets something cold it "explains" it by assuming it's wet. just like optical illusions are the brain "explaining" odd things in vision - so this is a kind of "warmth illusion".
posted by not sure this is a good idea at 5:56 PM on July 30, 2008


Why do cold clothes feel wet?

Because wet clothes feel cold?
posted by EndsOfInvention at 6:43 PM on July 30, 2008 [2 favorites]


When water changes state from a liquid to a gas, energy is absorbed from the environment (i.e. the liquid->gas state change is endothermic). This is why you sweat: your body releases liquid water, that liquid water evaporates — meaning it changes into a gas — and in doing so it sucks some heat away from your skin.

Wet clothes feel cold for two reasons: one is because of the endothermic evaporation reaction, which actually makes the clothes cold,* the other is because water is a good conductor of heat. Most "warm clothes" (wool sweaters, down jackets, etc.) keep you warm because they trap lots of air. Air is a good insulator, thus your body's heat is retained, and you feel warm. When you replace the air in the clothing with water — which is an excellent conductor of heat, compared to air — your body's heat is sucked away rather than trapped and retained. (This is also why standing in a room that's 65F/18C is fine, but being neck-deep in water of the same temperature would be chilly and potentially hypothermia-inducing.)

These two reasons work together to make wet clothes feel cold, and drain heat from your body. As water on the outside of the clothing evaporates, heat is lost to the atmosphere. But since the clothing is wet, it acts like a conveyor belt, moving heat from your skin directly to the outside of the clothing where it's lost via evaporation.

Some clothing (esp. wool and some modern synthetics) retain enough insulating qualities even when wet that they'll still keep you somewhat warm; others (like cotton) may not, and depending on the temperature and humidity, may be worse than wearing nothing.

As for your clothes that feel damp on the line but really aren't, I'm not exactly sure why that would be. I suspect part of it may be psychological — we sense dampness from a variety of factors, and temperature is one of them. (Warm = dry, cold = wet … which is why I've sometimes pulled stuff out of the dryer thinking it was dry, only to find it still damp once it cools.) It could also be that on a humid day, even with the clothes 'dry' to the point where their moisture content is the same as the air, they're still slightly more damp than you're used to having them. After spending a few minutes inside, where it's probably less humid (due to heating/AC), they lose the additional moisture and feel more typically dry.

* What I'm trying to get at here is that evaporation actually makes the clothes colder, in an absolute/measurable sense, while conductivity makes them insulate less well and makes you feel colder while wearing them. How much colder a wet piece of fabric will be, compared to a dry piece of fabric, depends on the ambient humidity and other factors. See dry bulb vs wet bulb for more information.
posted by Kadin2048 at 8:50 PM on July 30, 2008


What's also interesting is that very hot clothes can feel wet too. I have experienced denim heating up to extremely high temperatures when I'm standing near a heater, and it has a distinct wet feel to it.
posted by tomble at 9:55 PM on July 30, 2008


You can experience this sensation if you wear a pair of rubber or latex gloves and let extremely cold water run over your hands. They will feel wet.
posted by Deathalicious at 11:27 PM on July 30, 2008 [2 favorites]


The answer's been given - your skin interprets cold pressure as wet...

But as an aside - I find it fascinating that three people now have failed to read and interpret a six word question correctly...
posted by benzo8 at 3:32 AM on July 31, 2008


Related: why do simple questions invite confusion?
posted by fantabulous timewaster at 11:23 PM on July 31, 2008


your skin interprets cold pressure as wet

is that really an answer? isn't it just asserting the original question? don't you need to explain why that happens?
posted by not sure this is a good idea at 3:41 AM on August 1, 2008


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