Igloos

[Refrigerator]

Originally Posted by ppine

Igloo,
You must know more about this subject than the rest of us. I am confused. How can you put a roof on an igloo with loose grainy snow? What supports it?

I thought the same thing, but with the ice box grainy snow packs well and works fine. I have built 6 igloos with the ice box 2 with grainy snow with no problems.

[Igloo Ed]

I am not certain where your travels take you, Refrigerator, but given your area I would guess your low temps are around -10F. and that cold of snow can be very challenging to learn the packing feeling. It just needs to be more and more precise as the temps get colder. The first time I did it at -15F. I thought at first that would be the coldest I could pack in. But by the time I finished the igloo I was certain I could go colder. The same thing happened to me in Yellowstone at -27F. By the time I finished the igloo, I knew I could go colder yet.
Well, then the reason it works... There is a quasi-liquid layer on ice that exists until -40°
The layer gets thinner as the temps get colder and it disappears at -40°.
When pressing on/packing the snow, the ice crystals are pushed together with pressure and the liquid layer squishes out at the contact points where it instantly freezes to the original liquid layer depth. This process is called sintering, it is used in the manufacture of bronze oilite bearings. Little bronze beads are heated to within 5 degrees of their melting point, when the liquid layer appears on bronze, and then pressed together in a machine.
The trick is to pack only hard enough to sinter the snow but not hard enough to break the snow that has already been sinter below the new snow.
It's a feeling, just like skiing, and a feeling is hard to learn. I'm glad you got it Refrigerator.