Ironraven & Mr. Badger,

If you look at my original post, the comparison is between hot coffee/tea & cold soda/juice, the inference being that soda/juice is full of sugar (calories), and coffee/tea is not.

The heat in this case is the energy provided by the calories, not the actual temperature of the liquid. I believe the example given in the article states that the human body is made up of 15 liters of water, if you dump one liter of water heated to the normal temp of coffee or tea, it will only raise the temp of the bodies fluid by 3/10 of one degree.

I fully agree that all things being equal if the choice is b/t a hot beverage or a cold one, in cold weather the hot one always wins out.

That makes more sence then. I just skimmed the site that was sourced without reading it in depth.

Sorry, not true.

As a general rule, warmer fluids and gasses rise amongst cooler fluids and gasses, because they expand and become less dense (and therefore lighter) when heated - convection. I doubt that convection is that big a factor in how heat flows around the human body, given all the pumping, churning and general mixing of fluids going on.

I'd imagine that conduction is the dominant factor and (like radiation), it doesn't care which way "up" is.

There are exceptions to warmer fluids rising via convection, too. Between about 4 deg C and freezing water starts to expand again as it cools (and expands a whole lot more on freezing). This means that you can have cool water rising through warmer water via convection.

But, hats are good :-)

eeph

Ironraven, I was backing you . I too wear dark colors in winter, for the same reasons.
eeph, maybe standing still, not much. But, and I'm sure you seen it, looking at someone who has recently exercised, through a thermal lens, you can clearly see the excess heat rising off the body. Moreso in the head area, if thats its only vent out (due to clothing).
So, I think that convection WILL play a part in this, given the above situation. The human body will do what it can to release excess energy in the form of heat. HEat is transferred to the blood vessels closest to the surface of the skin. As there are far more of these on the head, than any other body part, due to the fact that the brain is selfish & will attempt to regulate its temp the best it can, it only stands to reason that we lose more heat through the head than other parts. Also, the head has little fat on it (for most of us ), and thus requires thermoregulation through convection.
Wow, ok, my brain now hurts. Alot.

While teh 70% figure is a little (or a lot) high, I will continue to cover my head when in extreme (hot or cold) temps. It may only be 9% or my skin surface, but it's still 9%. A wool blend beanie is much better than none.

Sorry, my brain is full of snot, I'm not thinking so well.

I actually hadn't even thought about the need to cool warm/hot beverages. If the core temp goes up, the body will send more blood to the extremities, improving your dexterity. Makes sense to me.

Consider the surface area of your head is the same as your upper back or chest (remember the rule of 9's). You wouldn't go out in 20 degree weather with your upper back exposed, would you?

Let me get this straight. I'm standing on the shore, my J3 Cub nosedown in an Alaskan lake.I managed to pull our survival kit out. My flight partner produces a quart of Florida Sunshine OJ and proceeds to drink. Meanwhile, to test this theory I am going to ingest a quart of Tea. And being irish I am from the highest per capita teadrinkers in the world ( 6 cups daily on average.)Now, has anyone considered any other factors in this test? Anyone? To drink Tea or Coffee I am going to BOIL water. I am going to have a FIRE. Bounces a valencia off the monitors of anyone who needs further explanation. I think these guys came up with this while standing hatless.

Some cacti will make you vomit if you eat the pulp or moisture it contains. Others will give you diarrhea. But getting past the darn spines will drive you crazy, anyway.

Moss grows where there is moisture and shade. A cluster of trees provides a lot of shade, and low branches provide shade, so moss grows all around the trunk. A single tree with limbs high enough to expose the trunk to the sun will usually have moss on it's north side. But not all growth on a trunk is really moss. It's good to know your mosses.

Sure, it's the calories that heat the stove, but if you're verging on hypothermia, do you really want Hagen Das? And I thought the doctor's example of dumping a quart (or whatever) of hot water into a larger amount of cold water was kind of stupid. You're pouring a cup or two of hot water into a bag the size of your fist (or two). It's going to stay there for a bit, then gradually flow into your small intestine. And it's going to cool down more slowly than his example.


If your feet or hands or other body part is cold, cover up whatever part is exposed. It doesn't matter how much body heat is lost through the head... in a cold situation, ANY is too much.

Sue

If I can manage to drag my SS thermos out of that Cub, we can sip on my hot coffee while the fire is heating the water for your tea. But I may never fly with you again...