I'm going winter camping in a couple of weeks. It will be at the limit of my sleeping bag comfort zone. We may be sleeping on snow. I plan to take my Big Agnes air Mattress and a closed cell foam pad like maybe my RidgeRest. The question is: do I put the RidgeRest on top of the air Mattress or the other way around. I am only interested in warmth, comfort either way will be acceptable to me.

The old theory was that air in an air mattress circulated cold air. But my new air mattress does have a small R rating and if it is on top of the CC Foam pad and covered by the sleeping bag where would the cold air come from? I have slept on snowand ice several times with just a 72" RidgeRest and was warm enough so I think it alone is pretty darn good insulation..