how An Igloo keeps you warm

Throughout history, both humans and various forms of life, including plants and animals, have utilized frozen "sky water" for warmth for countless years. This concept might seem contradictory, considering that snow is typically associated with cold temperatures. One might even describe it as incredibly cold. The origin of the first igloo builder remains uncertain, but snow, when appropriately constructed and in accordance with the principles of physics, can provide superior insulation and warmth compared to the interior of a tauntaun. Hence, the famous reassurance, "You'll be okay, Luke!" So, how does something cold manage to create a cozy environment?

The Arctic, a vast and icy region, is renowned as one of the most inhospitable environments on Earth. However, remarkably, the Inuit people have thrived in this harsh territory for approximately 5,000 years. In the expanse of the pack ice, winter temperatures plummet to a bone-chilling 50 degrees below zero. In such extreme cold, survival necessitates the discovery of shelter. Given the scarcity of forests in the area, nomadic hunters adapted by constructing shelters using the only resource accessible to them: snow.

Indeed, Eskimo languages possess numerous distinct words for snow due to the existence of various snow types. The choice of snow type plays a crucial role in determining whether an igloo provides warmth or transforms its occupants into "Homo sapiensicles." To comprehend this, it's important to grasp some basic knowledge about experiencing cold.

When your body temperature begins to decline, you sense heat escaping from your body. It's important to note that cold itself doesn't enter your body— in fact, the concept of cold is somewhat elusive. This notion might sound familiar, as it echoes a previously mentioned idea.

Imagine heat as a tangible substance that can be quantified: the more you give away, the colder you feel. This exchange of heat occurs through three different mechanisms: convection, conduction, and radiation. All three processes are at play within an igloo. When a person is inside, their body heat is radiated, moves around the igloo through convection, and is lost through the walls via conduction. This is analogous to what happens in your house, where insulation serves a similar purpose. In animals, living insulation functions in a similar manner. For example, fatty tissues like blubber help prevent heat transfer in whales and seals. However, animals without ample insulation employ a different strategy—they envelop themselves in air. The fur of sea otters, for instance, is approximately a thousand times denser than human hair. It's incredibly soft, but the key to its insulation capability lies in its texture.

Otter fur possesses a spiky texture, which enables it to trap air molecules effectively. This ability to trap air is precisely what snowflakes do as well. Fresh, powdery snow can contain up to 95% trapped air, making it an exceptional insulator. However, just like you need to pack snow tightly to form a snowball, loose snow isn't dense enough to construct with. Conversely, solid ice is suitable as a windbreaker but too heavy to lift easily.

Inuit hunters adopted a Goldilocks-like approach when it came to selecting snow for their igloos. The ideal snow for building igloo blocks is found somewhere in between. Instead of molding the blocks, traditional igloo builders cut them out of tightly-packed ground snow. This compacted snow is dense enough to provide structural support, while still containing more air pockets than a block of solid ice, making it relatively lightweight and a good insulator.

As is often the case, animals discovered this concept long before humans. Polar bears, groundhogs, and even birds like grouse create snow burrows to stay warm, utilizing the insulating properties of the snow.

Even before humans and animals, plants had already found a way to utilize snow as a protective measure against freezing. During the warmer months, the sun's heat energy accumulates in the soil. Similar to the roof over your head, a thick layer of snow prevents this heat from escaping upward. This covering of snow acts as a barrier, preventing ice crystals from forming inside the roots, shoots, and seeds of plants. Avoiding freezing to death serves as a significant incentive for any organism to become resourceful. However, our intelligent primate brains took it a step further by inventing igloos.

Igloos are engineered to optimize warmth and stability. While cartoon depictions often portray them as flat-bottomed half-spheres, their actual shape is quite different. If you were to slice a real igloo in half, you would observe a shape called a catenary. This gently sloping shape is the same as that formed by a drooping chain held from both ends. The catenary arch distributes weight more evenly than a half circle, without bulging or buckling. It is one of the most stable arch shapes found in nature, and its effectiveness is still recognized and utilized today.

Inside an igloo, different levels are carved to create distinct spaces. As hot air rises, it accumulates in the upper part of the igloo, while colder air sinks down into the lower section, away from the areas where eating, sleeping, and relaxing occur. Additionally, the body heat of the occupants gradually melts the innermost layer of the igloo walls, reinforcing the barrier between them, the insulating snow blocks, and the freezing external environment.

Living inside an igloo essentially turns a person into a living furnace. Over time, the temperature within the icy dwelling can remain approximately 40-60 degrees Fahrenheit warmer than the surrounding air. Furthermore, having additional occupants in the igloo intensifies the warming effect, providing even greater comfort. So, stay cozy, and keep your curiosity alive!