Sleeping on a cold night. How would you configure..

[VA S]

I am glad to see this question here. I have a reasonable amount of experience, especially when it comes to not being warm enough on a cold night. :( I have a blow-up R4 pad, a 'normal' tent, lots of wool/synthetic socks, etc. BUT, since getting more involved in winter camping and learning about this site I have come to see that the HOW and WHAT of layering is so important. (Always layered, of course, but not with any real thought behind it – just used a LOT>) SO now I spend time thinking about wind layers, breathable layers, vapor barriers, Capilene layers, etc….how to mix and match….what goes on top….etc. etc. !!!! It's great to learn from others experiences.

[Marko Botsaris]

OK, I'll bite.

My hypothesis is that the *order* of any fixed set layers will hardly matter at all, over the long term (say more than an hour), once the heat *flow* has equilibrated, as long as these two factors hold.

(1) There is no flowing air (i.e a "breeze") *inside* your bag, or *under* your quilt, which is presupposed to be the outermost "layer".

(2) The layers fit in such a way as to not compress any layer beneath them.

The physics to me says that after the heat gradient has reached its equilibrium (shouldn't take too long) then there should be absolutely no difference due to the ordering of the layers – the heat inside the innermost layer will be due only to the layers themselves and the heat your body generates and moisture it gives off. It is his this quasi-equilibrium, steady state situation, which seems to me to be the important one because that is the one that will determine if you finally get too cold at 2 am as the temperature goes down. I think I know how to prove this thermodynamically, though it sometimes works out if one actually does the calculations something pops uf that is a surprise. For now I'm going with my gut that the principle of detailed balance will insure that it will not make a difference.

What I see is people saying what they do, and it is usually the logical order of things in terms of *fit*. But I see neither physical reasons, nor actual evidence that varying the *order* of the layer matters at all. The layers, yes, order no. I'd love to be proved wrong because I love it when my physical intuition is wrong, even after so many years. That is the fun stuff. But there are only a few people on here that try to answer questions experimentally. This would be harder than usual to test quantitatively, unless you want to get into a freezer at a standard temperature with a thermometer.

Now *what* layers people use, and how they work in different conditions, that I'm always interested in hearing about, and yes, independently of hats gloves and pad. But that is not how the OP posed the question, in spite of the number of people who are answering it that way.

EDIT: OK, surface area certainly counts, so I do buy the advice from people to in effect " make a bag out of your puffy " . Also mitten are better than gloves for warmth, and so on. Otherwise the outermost layers surface area should be about the same if worn normally, regardless of *order* provided you don't compress anything, which is not good.

[Eric Blumensaadt]

James,

I once slept quite comfortably in a quinzhee snow dome in -22 F. with a -20 F. MH synthetic bag, polyester longies, wool balaclave and synthetic quilted sox over heavy wool sox.

With that same MH winter bag AND the expansion gore zipped open AND my WM 30 F. Megalite down bag inside I could easily do -40 F…. WITH a fleeced neoprene or Psolar face mask. I've tried that double bag setup and it is a perfect fit.

BTW->>> The WM Megalie 30 F. down bag with polyester long johns and Thermolite Micro insulated jacket and pants & balaclava I was cozy at 15 F. and still had enough room to move around inside the bag.

[Aaron D]

Mark,
I appreciate your insight. Perhaps what you hypothesize is true. I think your #2 factor is what part of this discussion is about. Is it smarter to wear the down jacket which means probably half of it will be compressed? Or does one drape it over his torso? Even lay it over the quilt? I think the anecdotal advice is interesting/valid to some degree. I'm not as scientific as some here are, just thought I'd solicit some ideas and opinions from those with experience.

[josh wagner]

i would look for some sort of rocky outcropping that i could tuck a fire up against and then sleep beside that – catching some warmth directly from the fire and some reflecting off the rock. this rock also will protect from the wind, which could be pretty unnoticeable, but will still steal warmth. the tradeoff is that you could put a hole in your down from embers…

[Marko Botsaris]

Aaron, fair enough.

Personally I now choose the non-subtle approach of conscious planned slight overkill when in doubt. I had many over-cold nights, some scary some just uncomfortable, when in the first throes of UL fever a while back, and eventually decided no more. In fact on one of the "scary" ones I was wearing almost exactly the equivalent of list you mention, but it was a little warmer and much wetter than your scenario.

[Author]

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