We've all heard that the people of the arctic, called the Inuit, once lived in igloos made of snow. Since snow doesn't seem like a very sensible building material, you might wonder how that could be. Today A Moment of Science asks, why build an igloo?
Surprisingly, snow makes good insulation. In physics, an insulator is a material that does not conduct heat very well, like an oven mitt. As an insulator, snow traps your body heat inside the igloo, eventually warming the space up. The snow also shelters you from the cold wind; in fact, an igloo is so airtight that you must poke air holes in it or you could suffocate.
How effective is an igloo? Well, using just a lamp for heat can raise the temperature inside to about 41 degrees Fahrenheit when the arctic air outside is minus 40 degrees. Although the igloo is efficient, the Inuit don't live in them anymore: no garage for the snowmobile.