Imagine that you’re walking on the snowy landscape of the Arctic tundra. Obviously, you start feeling cold with all the icy chill wind blowing around you. You frantically look around for shelter, but there is nothing but crystal-white snow all around you. Finally, you find an igloo, which is also made of snow! You enter the structure, and after a while, you are surprised to find that you start feeling warm!
An igloo, which is made of the same freezing snow that makes us cold, is also very good at keeping people warm. But how? How can something so cold make you feel warm?
Well, that has something to do with the amazing properties of snow and the structure of an igloo.
Since the whole igloo scenario is an interplay between coldness and heat, let’s begin by understanding what ‘hot’ and ‘cold’ actually mean.
Heat is a form of energy that can be transferred from one body to another. Heat energy moves from regions of higher temperature to regions of low temperature until the temperatures of the two regions become equal and result in thermal equilibrium.
This movement of heat can happen in the following three ways as explained in the diagram:
In short, the terms ‘hot’ and ‘cold’ actually describe heat itself. The bodies that lose heat get colder, while those that gain heat get warmer. So, when you feel cold, you are simply losing heat.
An interplay of these three mechanisms keeps an igloo warm. Let’s see how!
On a chilly morning, a relatively small piece of blanket can make us feel warm and cozy. A blanket doesn’t generate any heat of its own and it isn’t something you necessarily define as ‘hot’, so how does it keep you warm? Simply by trapping the body heat from escaping! A blanket in itself isn’t warm; all that it does is prevent the loss of our body heat.
An igloo works on a similar principle. The igloo acts as a huge blanket and confines a person’s body heat within its walls.
The key to a warm igloo lies in choosing the right raw material; and there are only two raw materials abundantly available in the Arctic—snow and ice.
An igloo is made of compressed snow. Compact hardened snow is a great insulator of heat because snow is nothing but semi-frozen water with roughly 95% trapped air. The air molecules trapped between the tiny ice crystals create air pockets, which act as excellent insulators that prevent heat loss due to convection. Thus, snow is the perfect material with which to build a warm abode amidst the freezing Arctic environment.
Unlike snow, ice is basically frozen water and does not contain a lot of air pockets, which makes it a bad insulator. Thus, snow is preferred over ice for the construction of igloos.
The human body converts energy from the food we consume into heat energy. This heat energy is lost from our body to the external environment through conduction, convection, and mostly radiation. The escaped heat moves around the igloo through convection and warms up some of the air inside it.
Since cold air is denser than warm air, the cold air settles at the bottom of the igloo, while the warm air moves up towards the top of the structure. Catering to this, the igloo floor is divided into layers. The upper warm layer is where people sleep, the middle layer is for cooking and fires, and the bottom sunken floor acts as a cold sink.
The insulating snow walls prevent the loss of body heat and also protect people from the cold wind blowing outside.
Thus, an igloo makes use of the very body heat in order to regulate the temperature inside .
The structure of an igloo also plays an important role in confining the heat inside.
The small door and the tiny tunnel leading to the central dome of the igloo have their own significance. The small sunken right-angled tunnel acts as a cold sink, while also preventing snowstorms and cold winds from blowing directly into the main compartment of the igloo.
Have you ever thought about why igloos are shaped like domes? Why aren’t there any cubical igloos? Well, the shape of the igloo determines its stability. The dome of an igloo is shaped as a catenoid. This shape provides structural stability and ensures that the igloo doesn’t buckle or collapse under pressure.
If built right, an igloo can create a difference of about 40℃ between its interior and the external environment, just through the use of body heat.
In a study conducted, it was found that inside an igloo, near the bodies of the people, the temperature was around 36℃. In the air surrounding the people, the temperature dropped to almost 16℃ and at the far end, near the walls of the igloo, the temperature was around 1℃. Also, if there are more people inside the igloo, it gets even warmer.
Even though 16℃ or 1℃ isn’t exactly ‘cozy’, considering that the temperature of the Arctic terrains can reach a staggering -40℃ to -50℃, an igloo does a great job of regulating the temperature. Thus, for people living in sub-zero temperatures, an igloo makes for a toasty abode.
Igloos can keep us warm just like wool. For more on that read “How does wool keep us warm?“.
Raza has been writing since 2008, be it fiction, poetry, or articles on science, politics, and history. He believes that words can change the world, and he uses them to inspire and empower people through his writing. When he is not working, he is watching nature documentaries or playing with his cats.
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