Me and a couple camping friends were talking today and came up with an interesting question.
Suppose you were mountain climbing or whatever. You ended up in a completely snow covered valley that you knew you would not be able to climb out of until morning. You lost all your equipment except the clothes on your back and your trusty mummy bag rated at -30, no waterproof shell. You know that there in no chance you are going to stay awake, and need to go to sleep. The question was, are you more likely to survive if it is 30 or -30 degrees out. Those extra 60 degrees at first seem to be the a major advantage. However, at 30, the snow would be slushy and wet, and the heat leaking through the bag might be enough to melt the snow surrounding you. The water would soak into the bag, through your clothes, and likely you would die of hypothermia. On the otherhand, at -30 the snow is probably going to be hard frozen and powdery providing perfect air pockets and insulation like a insulating pad allowing the bag to live up to its full -30 rating(assuming no wind in either case.)
Just curious what anybody else thought of this puzzle, and did we miss anything.
Hypothermia cases are much more common above freezing temperatures than below in part because of the effect you describe-- wet clothes are deadly. Snow is in fact an excellent insulator and snow caves and such are the reasoning behind that. Igloos aren’t ‘traditional’; they are the result of the Primus Stove.
You’d want to dig a snow cave – if you know how to do it well, the temperature inside will be 32 degrees fahrenheit.
Where I am from, the last time it snowed was 1921. So IANA snow expert – I have no idea whether colder snow would be easier to make into a snow cave or not.
I guess it also depends on whether you have a down bag or a synthetic one. Down will lose all insulating properties if it gets too wet, whereas a good synthetic insulator will retain loft to a certain extent. I don’t know how wet you are likely to get just by sleeping on snow without waterproofing, but I imagine that it might make a difference. Me, I’m a desert camper, so I should probably not try to field this one.
I think you would be much better off at 30 in this situation, wolfman. It’s overnight and the valley is snow-covered, so if there is any slush on the surface (from the sun’s rays) you just have to move it as best you can and/or burrow into the snow. Your sleeping bag isn’t going to let enough body heat out to melt enough snow to soak through it.
Got a cite for this Tedster:
Might not be part of your tradition, but the Inuit were making igloos long before the Primus stove was made.
Yes, I’d like a cite as well. I imagine the Inuit will be fascinated by this little historical tidbit. Of course, if you define a seal oil lamp as an early Primus Stove, then you might have something there…
Back to the OP, I think you’d be better off at -30 and hiking in areas like you’ve described at those temperatures is foolhardy to the point of stupidity. Snow at that temperature is bone dry, but it doesn’t pack worth spit. If you find a deep enough drift, the top will usually have crusted enough to support digging a snow cave.
Further survival notes: frequently, valleys like the one you describe are treed. Break off branches to provide extra padding between you and the ground. Never never never go out in the bush like that without a lighter in each pocket, matches in your backpack, and more matches in your jacket. After twenty-mumble years in the Yukon, it’s automatic.
The security people in Vancouver airport get really shirty about multiple lighters and matches…wonder why…
