How Can You Stay Warm When Your Walls Are Made of Snow and Ice?
Though almost no one lives permanently in an igloo in the 21st century, there was a time when most Inuits in the central Arctic region constructed temporary homes out of snow and ice to get them through the winter. In the 21st century, they are used almost exclusively as temporary, emergency or hunting shelters by persons in the Arctic.
How Is an Igloo Constructed?
Igloos are typically built from what is commonly referred to as “hard snow,” a wind-packed substance that is hard and strong enough to be cut into blocks (significantly larger than cinder blocks, usually measuring 1x1x3 feet). Special “snow” saws are often used, but knives are also common. The blocks are customarily cut from a single trench and are angled slightly forward so that they lock in place. Construction follows a spiral pattern, with blocks getting progressively closer together the higher they go up. Most igloos feature a dome and are about 15 feet in diameter and about 10 feet tall in the middle, accommodating three-to-five people.
After the keystone is placed to seal in the top of the dome, an entrance is dug below ground level and a hole is made in the top for ventilation. Any gaps between the blocks are then packed with loose snow, which acts as a mortar further insulating the structure.
How Do People Stay Warm in an Igloo?
A couple factors contribute to a person’s ability to be comfortable in a structure built entirely out of snow and ice:
- The below ground entrance acts as a “cold-air sink,” pulling the coldest air below the living space
- The compacted snow acts like the walls of a thermos, blocking trapped air that acts as insulation. Because the snow offers such good insulation, body heat alone can often be enough to make the interior comfortable. In addition, most sleeping berths are elevated, taking advantage of the fact that warm air rises.
The insulating properties of snow can allow it to be up to 60 degrees warmer inside an igloo than outside.
