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Old 10-20-2016, 09:58 PM   #1
Tallor
 
Join Date: May 2016
Default Coldness, Wind Chill, and Survival

Once again I return to a question I asked myself when I first read GURPS: Campaigns... isn't 35*F WAY too cold for someone to live indefinitely? As someone who lives in a pretty warm climate, I'm not sure I'd be too comfortable at 60 degrees, and I feel like plenty of humans would be doing HT rolls around 40-50, not a mere 3F above freezing!

I'm not really a master in biology though, so I'm not sure how an average, non-desert-dwelling human would do in cold weather. The numbers just seem odd to me.
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Old 10-20-2016, 10:32 PM   #2
Euthoniel
 
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Default Re: Coldness, Wind Chill, and Survival

Remember that the human body puts out about 100W of energy, so it generates heat on its own. 35*F is a little generous for indefinite survival, but not out of the realm of possibility.

Here is a well researched graph that shows human survival conditions for temperature.

Last edited by Euthoniel; 10-20-2016 at 10:38 PM.
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Old 10-20-2016, 10:54 PM   #3
Flyndaran
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Default Re: Coldness, Wind Chill, and Survival

I don't see any mention of what clothing these people were wearing.
Also that 100 Watts is average throughout the entire day for average adults making it almost useless trivia.
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Old 10-20-2016, 11:19 PM   #4
Euthoniel
 
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Default Re: Coldness, Wind Chill, and Survival

It's not useless info because it takes humans a long time to die from hypothermia at the temperatures the OP is talking about. Sure, the exact amount of energy is not important, but the point is that humans generate energy and heat. If we didn't, we'd die faster in the cold and at lower temperatures.
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Old 10-20-2016, 11:21 PM   #5
David Johnston2
 
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Default Re: Coldness, Wind Chill, and Survival

Quote:
Originally Posted by Tallor View Post
Once again I return to a question I asked myself when I first read GURPS: Campaigns... isn't 35*F WAY too cold for someone to live indefinitely? As someone who lives in a pretty warm climate, I'm not sure I'd be too comfortable at 60 degrees, and I feel like plenty of humans would be doing HT rolls around 40-50, not a mere 3F above freezing!
The built in assumption is that you are not naked. 35 degrees is a point where...if you are fully clothed, including a winter weight coat, you are no danger of freezing to death no matter how long you are out of doors. You can sleep on park benches all night in those temperatures and be in no danger. You might not be comfortable, if you are accustomed to a warm climate, but actually slightly above freezing is when I find myself uncomfortably warm while walking across town in my sweater and winter coat. Strip me naked and dump some water on me and HT rolls would start being called for.

Last edited by David Johnston2; 10-21-2016 at 01:32 AM.
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Old 10-21-2016, 12:13 AM   #6
Flyndaran
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Default Re: Coldness, Wind Chill, and Survival

Quote:
Originally Posted by Euthoniel View Post
It's not useless info because it takes humans a long time to die from hypothermia at the temperatures the OP is talking about. Sure, the exact amount of energy is not important, but the point is that humans generate energy and heat. If we didn't, we'd die faster in the cold and at lower temperatures.
Humans are extremely well adapted to hot dry equatorial regions. Naked we die in the cold much faster than most other mammals.
There is also lots of individual variation especially when dealing with down time as basal metabolic rates vary even more.
Since going past 40, I can now run in 103 F, when in my 20s I literally suffered heat exhaustion in 82 F. But I now sometimes wear a coat indoors when it dips below 70.
I know I would risk hypothermia in light clothing after a few hours anywhere near 32 F.
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Old 10-21-2016, 12:17 AM   #7
McAllister
 
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Default Re: Coldness, Wind Chill, and Survival

I've always wondered what use you could put high levels of Temperature Control to. I'm still wondering, of course: absent a detailed table of what materials suffer which conditions at a given temperature, I'm not going to have any idea how to make cold stone brittle or hot metal soft. But it seemed relevant.
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Old 10-21-2016, 12:22 AM   #8
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Default Re: Coldness, Wind Chill, and Survival

Quote:
Originally Posted by Euthoniel View Post
Here is a well researched graph that shows human survival conditions for temperature.
Sometimes it feels like my job is slowly killing me, but, according to that chart, my employer seems to have been actually trying to murder me.
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Old 10-21-2016, 01:26 AM   #9
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Default Re: Coldness, Wind Chill, and Survival

Quote:
Originally Posted by Tallor
Once again I return to a question I asked myself when I first read GURPS: Campaigns... isn't 35*F WAY too cold for someone to live indefinitely? As someone who lives in a pretty warm climate, I'm not sure I'd be too comfortable at 60 degrees, and I feel like plenty of humans would be doing HT rolls around 40-50, not a mere 3F above freezing!

I'm not really a master in biology though, so I'm not sure how an average, non-desert-dwelling human would do in cold weather. The numbers just seem odd to me.
Note that the situational modifier giving a +0 modifier to the HT Roll is ordinary winter clothing (table on B430). Provided you don’t let your clothing get wet or dirty, you really can survive indefinitely at 35F. It’ll probably help if you’re given some idea of what constitutes ordinary winter clothing and how that contrasts with Arctic clothing. I’ve worn both, though I haven’t needed Arctic clothing since leaving the military. For our purposes, we are discussing those garments that make a direct contribution to warmth and, where relevant, choice of materials and essential environmental gear. One other point, and apparently people who don’t deal with cold environments aren’t aware of it. Cold-weather clothing cannot make you warm. Cold weather clothing keeps you warm by preventing heat loss. Without a heat source, putting cold weather clothing on after you’re cold is useful only to the degree that it prevents further heat loss.

Most people who need to wear ordinary winter clothing, or Arctic clothing for that matter, dress in layers. This allows them to adjust for temperature by adding or removing garments as necessary. For our example, we’ll use garments typical for the early 1960s which were fairly heavy and made little use of synthetic materials. Modern synthetics can give the same insulation value with a lower weight. From the skin out, ordinary winter clothing (for a male) consists of: thermal underwear (waffle-weave longjohns or separate drawers and shirt, net-style underwear also works), wool socks, flannel shirt, wool pants, wool sweater, wind pants (lined jeans work in lieu of the wool pants/wind pants combination) or ski pants, mackinaw jacket or parka-style with hood or a ski jacket (the difference between a parka and a ski jacket is length, a ski jacket stops at the waist, a parka covers the hips, possibly the thighs as well), wool inner mittens, leather outer mittens, a wool scarf or a balaclava (which drops the need for a cap), a warm cap (astrakhan, Klondike, melton or ski cap, with a mackinaw-style coat or a tuque [either watch cap or stocking cap style], with a parka style, depending on your region), optionally ski goggles, and shoepaks (shoepaks are much like mukluks but typically have rubber outers up to about ankle height. They’re preferred for places that have an extended slushy season.) or lined boots. Wool/flannel is the preferred material for warmth, nylon, canvas, silk or leather is meant to protect from the wind. Wool/flannel have tiny air pockets between the fibers and it is those air pockets that provide the actual insulation once your body warms the still air up. While cotton is warmer than wool/flannel, it’s use in winter clothing is avoided. Dry cotton is warmer than dry wool but wet wool is much warmer than wet cotton. The tighter weave materials ensure that the warmed still air isn’t carried away any faster than can be avoided.

Arctic clothing gets a bit more involved. Again from the skin out, thermal underwear, 2 pairs of socks (either one pair nylon and one pair wool, the nylon to avoid blisters from the wool sock bunching, or two pairs of wool socks, but one pair has to be a larger size to maintain insulation), wool pants, flannel shirt, wool or flannel pants, wool sweater, wind pants*, thigh-length parka with hood* (with a wolverine fur ruff to prevent frost condensation from your breath), balaclava and scarf, wool inner mittens, leather outer mittens (these differ from ordinary winter clothing by being gauntlet length [almost to the elbow], rather than wrist length), felt insoles, freize socks (essentially two blankets cut into socks and sewn together at the cuff to create a double thick sock), mesh insoles, mukluks* (knee-length boots) [Note: modern Sorrels, and their equivalents, are commercial versions of the mukluk/freize socks combination, usually in a shoepak format.] optionally a mouth cup (looking like a dust mask but used in arid Arctic areas to prevent the mouth and nasal cavity from drying out), and snow goggles (these are not optional and are not the same thing as ski goggles. Snow goggles were constructed from thin pieces of wood and were worn like eyeglasses. Vision was through a small slit cut in each “eyepiece”. They prevented snow blindness from the glare of the reflected sunlight on snow. The only acceptable substitute for a pair of snow goggles is a pair of polarized sunglasses.

Arctic clothing typically has large buttons that can be manipulated without removing one’s mittens and where possible zippers are backed up with buttons. A common feature on Arctic clothing and sleeping bags with metal zippers is a buttoned “storm flap” of cloth that covers the zipper to minimize its heat loss.

* assuming traditional materials, these would be worn in two pieces, the inner piece is worn skin-in, fur-out and the outer piece is worn skin-out, fur-in, giving a fairly thick zone of still air with good protection from the wind.

Gloves are typically worn only inside a tent and only when finer manipulation is required. Like the mittens, gloves consist of a leather outer and a wool knit liner. The sole exception are anti-contact gloves, which are unlined and used to handle metal objects in the arctic. In Arctic conditions, human flesh will freeze to metal (such as the barrel of your rifle or the handle of your water bottle cup) and come off on the metal, anti-contact gloves protect you from that.

If sleeping in a tent, igloo or snow trench rather than a heated house, there are a few appropriate points regarding clothes and sleeping bags. Wherever possible, it is preferable to sleep nude, or as close to nude as possible. The human body gives off perspiration while sleeping and it will collect in any clothing worn, making it cold and clammy. For that reason, you do not put your clothes in your sleeping bag with you “so they’ll be warm when I wake up”. Clothes are typically hung up on a cord and any frost from condensation beaten off on awakening. The clothes will warm up within five or ten minutes of dressing. The sleeping bag is aired out to get rid of the condensation in it.

A winter sleeping bag doesn’t differ appreciably from an Arctic sleeping bag, although Arctic sleeping bags tend to be exclusively mummy-cut while ordinary winter sleeping bags may be rectangular cut. The insulation filing is down, preferably eiderdown as it has the most air pockets, feathers are right out. A typical sleeping bag has three layers, a flannel liner, the sleeping bag or inner sleeping bag and the sleeping robe or outer sleeping bag, optionally, an arctic sleeping bag may have a hood as well. Like a regular sleeping bag, winter and arctic sleeping bags are used in combination with a groundsheet and air mattress.

Quote:
Originally Posted by Euthoniel
Remember that the human body puts out about 100W of energy, so it generates heat on its own. 35*F is a little generous for indefinite survival, but not out of the realm of possibility.

Here is a well researched graph that shows human survival conditions for temperature.
The graph isn’t directly relevant to the question as it is talking about the core temperature of the human body rather than ambient air temperature. Winter clothing and Arctic clothing will help keep the core body temperature at 98.6F. When the body's extremities drop below 98.6F, there is a danger of frostbite eventually setting in. IIRC, typically around a body temperature in the affected part of about 50F.

Quote:
Originally Posted by Flyndaran
I don't see any mention of what clothing these people were wearing.
Assuming you’re responding to the graph Euthoniel linked to, clothing is irrelevant. Once core body temperature drops, clothing has been by-passed.

Last edited by Curmudgeon; 10-21-2016 at 01:51 AM.
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Old 10-21-2016, 01:31 AM   #10
Flyndaran
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Default Re: Coldness, Wind Chill, and Survival

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Originally Posted by McAllister View Post
I've always wondered what use you could put high levels of Temperature Control to. I'm still wondering, of course: absent a detailed table of what materials suffer which conditions at a given temperature, I'm not going to have any idea how to make cold stone brittle or hot metal soft. But it seemed relevant.
Generally, if it causes structural damage, then it's damage not fatigue based temperature issues. Fireballs cause burning not fatigue, for example.
When that point gets crossed involves FAR too many variables for any playable game to cover.
Water doesn't have to be fire hot to injure or kill. People can momentarily dip their hands in molten lead or carefully ingest liquid nitrogen without injury due to their very low thermal conductivity.
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