As counterintuitive as it sounds, eskimos have been using snow for hundreds of years to hide away from the frigid cold. But how can snow protect you from the cold? The answer lies in the basic method of construction.
Igloos are built from compressed snow, which is sawn directly out of the ground. These blocks are stacked around the hole, and since snow has many air pockets per cubic foot, it is a great insulator along with being light and stable. The heating mechanism inside could be a fire or just the body temperatures, but the insulating powers of snow are the real reason behind their effectiveness. The catenary shape of the igloo, the one which occurs if you hold a chain from its ends and let it drop, allows the structure to remain highly stable and resist strong wind gusts.
Back to the temperature now. Along with the air pockets in the snow, the inside of the igloo is also terraced, meaning people sleep at the uppermost level of the steps while the middle level is used to light fires and other household activities. The bottom level is a “cold sump,” and all of this is derived from the simple rule of how hot air rises and cold air sets at the bottom, thus allowing the parts closer to the roof to stay warmer.
The temperatures inside the igloo can go up to 20 degrees, and depend on the number of people inside the structure. While 20 degrees might not sound very comfortable, it is a welcome difference considering the outside temperatures dropping as low as -50 degree Fahrenheit.
Watch the video below to learn more about the physics of igloos.
Here’s a rare video on how Eskimos actually build an igloo!