How igloos keep people warm?!

Imagine yourself in the coldest part of Arctic, ice-cold winds are blowing and the temperature is about -45 degree Celsius. You might consider a thick-walled house (with smoke coming out of the chimneys) to be your last hope of survival. Consider again, because all you need to survive those ice cold winds and bone-freezing temperature is snow, a lot of snow. But not to build a snowman, rather to build a big halo snowman-tummy, with…