/ Snow/glacier sleeping. COLD - was it gear choice?
Last year we bivvied on snow on a glacier in Austria summer at 2750m. Wind came in and it got pretty chilly - started snowing so I guess it was around zero with some wind chill. Three nights little sleep, cold "creeping" up from the snow but also extremities. Not fun! When sleeping on rock at same altitude it was much warmer.
Gear was, Rab Neutrino 200, Thermarest Z-lite matt and alpkit bivvy bag. Plus I was wearing Montane Smock and climbing trousers and hat in the bag. Usually I am not a cold person. Aware the bag was a little lean for the conditions but didn't expect to be that chilly.
This September we are going to be camping at about 3300m in French Alps. We are bringing a tent (Mountain Hardware Ghost UL2) with give us more shelter but will that be enough to stave off the cold? Have an foam/inflating matt combo which I think would be warmer but would a new bag be the way to go? What about some Scottish Winter style base layers?
The double mat combo will help, especially if the inflatable has a decent R value.
A snow wall and or snow valances will stop the cold wind blowing directly between the outer and inner tent. Plus better ground insulation as said above.
I think there are inflatable down mats for sleeping on snow
I go for two foam mats on snow and it's fine, they go on the outside of the pack rolled together so the bulk doesn't matter. I've had a few of the inflatable mattresses, but always go back to the foam as they're more durable and more useful (3 people lounging about on an inflatable mattress is not a good combination!)
I'd recommend a smooth one as the second and use the the thermarest on the bottom, it's too hard to keep snow out of the dimples, where it melts and spreads, put a smooth one on top and it's easier to brush snow off.
I suspect your mat is the problem here. In the late 1980's and 1990's I spent many a night bivvied on the Col du Midi, at over 3000m. Sometimes in a tent, sometimes a bivvi bag. Covered in deep frost every morning.
I was never cold during the night, and my sleep was only disturbed by fear at the following day's activity. Always used the full on expedition Karrimat (with the black underside), and a Rab 1000g fill bag. Only kipped in thermals.
As others have said, go for a really good mat (or mat combo) and also sleep on top of rucsac, ropes and any other kit you have to minimise heat loss to the snow/ice.
A proper 4-Season mat like the Thermarest NeoAir X-Therm is worth at least 200g of extra sleeping bag fill compared to a Z-lite or a bog standard self-inflating mat.
Rab Neutrino 200 is rated comfort 6.5, limit 1.5. Sleeping bag ratings are a bit random and if anything tend to overestimate how warm the bag is. 2,750m sleeping directly on glacier could easily be below zero even in summer. Depends on the freezing level but even on a relatively warm night it's unlikely to be anything like 6.5C. So get a warmer sleeping bag... Something with a comfort rating of at least -5 would be sensible.
I don't know about your mat, it may be ok. I've found the Neoair XLite to be fine sleeping on a glacier in March (it would have been a few degrees below zero) but with a -18 bag plus bivvy bag. The main concern with the XLite is puncturing it, though I've found it surprisingly robus on rocky bivvys. Not really an issue on a glacier.
I'd say a base layer is always a good idea. I know the Montane stuff is meant to work without but equally I'm not sure they're designed for sleeping in when you won't move around for many hours.
Thanks for the replies... its the question of can a thicker matt add warmth than a thinner bag has not got... Some seem to think so. Maybe I need more whiskey
What did you do immediately before getting into your bag on each occasion? If you get your blood flowing immediately before getting into your bag, you'll be warm and hopefully stay warm. If you sit about then get in cold, the best insulation in the world won't be able to make you warm.
Your mat is insulation from the ground, it’s very important.
I'd always understood that the insulation value from down came from its ability to loft and trap air : but in a sleeping mat (whether foam or self inflating) the gas is trapped in the mat anyway so does the down really make a significant difference or is it just a placebo type effect?
I should add this isn't intended to be some passive aggressive criticism of your contribution, it is a genuine enquiry and I'd be interested to hear an explanation of the down mat mechanism .
I think the concept in the case of Exped mats at least is that the insulation fills the space between the top and bottom layers of the pad and prevents convection currents from sapping your heat as they do in air beds.
I suppose their efficiency depends on how well the insulation traps the air in place. In the Exped specs the down mats tend to have much higher R values than the synthetic mats.
I'd wondered if inhibition of convection was important but when the warm body is above the cold ground wouldn't that mean that the air warmed by the body would naturally float at the top of the mat anyway...I'd have thought convection would only be significant where the heat source was at the bottom so that less dense gas moves away from the warmer region? E.g. If you put an immersion heater in the middle of your water tank it doesn't heat the whole tank.
Maybe what is significant rather than purely convective air flow is the air flow through the mat due to the movement of the sleeper ( which must act a bit like a bellows /pump) which in a single envelope of gas would very effectively mix warm and cold regions and perhaps it is these flows which are inhibited...it's almost possible to imagine frictional heating of moving air moving through a sufficiently resistive medium. I think I may have (happily and unexpectedly) answered my own question ?
Just to touch on your third question - base layers. Having seen Andy Kirkpatrick's comments I'm a recent convert to the Brynje. Good all round but for sleeping I find them excellent in terms of moisture transport. I say good all round but still can't help thinking of Rab C Nesbitt...
Unless you can find a very sheltered spot I'd say your tent will be somewhat lightweight that high up. We use exactly the same tent and although the quality is excellent I wouldn't call it a mountaineering tent. Good luck though.
Yes. I heard a story the other day from a friend who found a piece of block insulation in a crevasse which he hauled out and slept on. Was the warmest in the bivvy in the lightest bag.
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