interesting

[Dan00001]

Yep, and I see it stated quite often in Facebook groups. Of course, the more of your body you have covered up, the less convective heat loss, the warmer you will be.

Here's another Myth that I see quoted fairly often, that 'One pound on your foot equals five pounds on your back'. iirc, in the studies conducted, heavy footwear made some difference at running speeds but at normal walking speeds, the difference in energy output was negligible.

 

[Dan00001]

That doesn't apply when wearing clothing, which insulates and traps heat. Prevent the majority from escaping. Heat rises, and blood flows. If you have no insulation on your head, then that would be a primary source of heat loss. You can warm your hands up by putting a hat on, but you can't warm your head up by putting gloves on.

Yes, but that's more because of your bodies response system restricting blood flow. Warming your head isn't directly producing more heat for your hands, it's simply your body allowing blood to flow to your hands and feet again once it's satisfied that your head and/or core organs are sufficiently warm again.

 

[HillBill]

Yes, but that's more because of your bodies response system restricting blood flow. Warming your head isn't directly producing more heat for your hands, it's simply your body allowing blood to flow to your hands and feet again once it's satisfied that your head and/or core organs are sufficiently warm again.

Yeah, that's how i've always understood it. Which is why i made the point of it not working vice versa.

 

[Dan00001]

I find it quite interesting, the book I'm currently reading, 'Keeping Dry & Staying Warm' talks about it a bit. When it's warm, your body will increase blood flow to your extremities in an attempt to cool down, causing your hands and feet to sweat more, and in some people can cause swelling of the hands and feet.

I've always hated the feeling of hot, sweaty hands, and my reaction has always been to place my hands near or on something cold which achieves nothing, when what I should have been doing is attempting to cool down my body instead.

 

[Toddy]

I think they're asking the wrong question, and the wrong way around.

The head has masses of blood flow (scalp wounds bleed profusely kind of thing) and the brain is preferentially favoured with decent blood supply.

Percentage wise you won't lose 'most' heat from the head, but covering it up helps keep us so much warmer.....it's like windchill that turns a reasonable temperature into a miserable bitter icy cold experience.
Frost bite on ears, noses, lips, chins and cheeks is most definitely not fun.....even if we don't lose 'most' heat from there.

Cover up, stop the heat loss and we're fine. Too warm, open up clothing, etc.,

 

[Toddy]

I find it quite interesting, the book I'm currently reading, 'Keeping Dry & Staying Warm' talks about it a bit. When it's warm, your body will increase blood flow to your extremities in an attempt to cool down, causing your hands and feet to sweat more, and in some people can cause swelling of the hands and feet.

I've always hated the feeling of hot, sweaty hands, and my reaction has always been to place my hands near or on something cold which achieves nothing, when what I should have been doing is attempting to cool down my body instead.

When pregnant in a really scorching hot summer, I was told to run cold water over my inner wrists...the skin is thin there and the blood is near the surface. It cools down the blood, cools down the whole body.
That's why in the cold we wear long cuffed gloves, etc.,

 

[Toddy]

Yes, that is correct, and imo, logical. If I were to walk around with no trousers wearing a woolly hat, I'm pretty sure that I would be more cold.

The studies concluded that heat loss is roughly proportionate to surface area i.e your head at ~7% of your bodies surface area loses ~10% of heat.

Highlanders didn't find it so
Kilts and blue bonnets

 

[Dan00001]

When pregnant in a really scorching hot summer, I was told to run cold water over my inner wrists...the skin is thin there and the blood is near the surface. It cools down the blood, cools down the whole body.
That's why in the cold we wear long cuffed gloves, etc.,

This is not wrong, but I have seen people stating that 'you lose most of your body heat through head and wrists', which is incorrect.

But what you said is definitely true and also the opposite, in cold weather, wrist warmers will keep your hands warmer as the blood flowing to your hands will stay warmer. Wrist warmers are especially recommended to those who suffer with Raynaud's.

 

[Dan00001]

I'm rambling now, but another thing I found interesting in this book was about Bedouin (Who live in the desert areas of the Asian middle-east) and who wear robes..

"Bedouin robes are worn loose. Inside, the cooling happens by convection - either by a bellows action, as the robes flow in the wind, or by a chimney sort of effect, as air rises between robe and skin." They also added that the increase rate of air movement improved the rate of evaporative cooling.

I've been wondering about trying a loose and breathable poncho during the warmer months instead of a coat. I quite fancy trying the Paramo poncho.

 

[Keith_Beef]

When pregnant in a really scorching hot summer, I was told to run cold water over my inner wrists...the skin is thin there and the blood is near the surface. It cools down the blood, cools down the whole body.
That's why in the cold we wear long cuffed gloves, etc.,

If I'm feeling hot, I'll run cold water over my wrists or plunge my wrists into a cold river; conversely, a good way to warm up is to run warm water over my wrists.

But watch out! When your skin is cold, it looses sensation, so running really hot water straight from the hot tap onto very cold skin can scald you before you feel any pain.

 

[C_Claycomb]

yep. I always thought that a person lost way more heat through their head. Hot air rises was what I thought. Turns out that according to the studies that is simply not the case x

Heat does not move through your body by convection. Heat does not rise. Hot air rises.

I'm rambling now, but another thing I found interesting in this book was about Bedouin (Who live in the desert areas of the Asian middle-east) and who wear robes..

"Bedouin robes are worn loose. Inside, the cooling happens by convection - either by a bellows action, as the robes flow in the wind, or by a chimney sort of effect, as air rises between robe and skin." They also added that the increase rate of air movement improved the rate of evaporative cooling.

I've been wondering about trying a loose and breathable poncho during the warmer months instead of a coat. I quite fancy trying the Paramo poncho.

In addition, what I have been told is that the robes block the sun from causing sweat to simply flash dry from your skin. It forms something of a higher humidity micro climate where the heat to evaporate sweat has to come from the skin, not from sun working with a very dry wind.

 

[Broch]

On top of all that, most Bedouin robes are black which, I am told, improves the convection flow past the body (I have always struggled with the logic but I know it works!).

 

[Pattree]

I think that their sheep are black!

 

[Broch]

There are few sheep, mostly goats, and they vary in colour. Also, I don't think they are beyond using a bleach if it made them more comfortable

 

[TLM]

Heat does not move through your body by convection.

A slightly differing opinion here, blood when moving around carries heat by kind of convection but of course the process is different from warm air rising in a cooler surrounding.

 

[C_Claycomb]

A slightly differing opinion here, blood when moving around carries heat by kind of convection but of course the process is different from warm air rising in a cooler surrounding.

Oh for heavens sake. No, you are not expressing a different opinion to mine, you are just being pedantic about how I expressed an idea.

Dale was talking about his head losing heat...and connected the idea of heat rising. Hot blood doesn't rise to the top of your head by being less dense than cold blood, nor is one part of the body hotter than another because "heat rises".

 

[C_Claycomb]

On top of all that, most Bedouin robes are black which, I am told, improves the convection flow past the body (I have always struggled with the logic but I know it works!).

I have struggled with this idea too. Black certainly creates darker shade than white cloth, since it absorbs more sun. I thought that was the intent, which makes sense if the cloth or layers are not all that thick or are of loose weave. That some in the Middle East wear black, while lots of others wear white or pale colours has always made me question whether it is more a style and tradition than a difference that has evolved to confer an advantage.

 

[Broch]

Possibly, but the Bedouin of the Algerian and Moroccan Sahara are predominantly robed in black - Arab dress of the towns and other countries tends to be white or, sometimes, blue. When I asked an Arab guide why they dressed in black he just said 'because it's cooler' without any explanation

 

[TLM]

Oh for heavens sake. No, you are not expressing a different opinion to mine, you are just being pedantic about how I expressed an idea.

Pedantic, that's me especially concerning definition of terms; a fluid carrying heat somewhere ...

I still think most of this discussion is moot as I am still almost certain that US army studied a fully clothed man in military winter gear. That guy is actually losing a lot of heat through his head that is more exposed than the rest of him.

 

[Dan00001]

On top of all that, most Bedouin robes are black which, I am told, improves the convection flow past the body (I have always struggled with the logic but I know it works!).

It mentions that in this book, but it also doesn't say why exactly, just that that's what the study found.