How a Snow Hole Becomes an Igloo

3-Second Blueprint (English)

1. Leaning hard-packed snow blocks inward along a continuous upward spiral builds a self-supporting dome that resists collapse and Arctic winds.
2. Digging the entrance tunnel below floor level traps dense cold air at the bottom while a raised snow bench captures rising warm interior air.
3. Melting and refreezing inner walls creates an airtight ice shell that, paired with a roof vent, lets body heat hold above-freezing warmth.