Igloos & Snow holes (conduction convection radiation)

CONVECTION CONDUCTION RADIATION

“Hot air rises, Cold air falls”

The Eskimos use this to their advantage, when living in an igloo or snow hole/cave. One example is the place they sleep, this is constructed at a higher level where there is more heat, and the entrance is built at a lower level to direct cold air out.

A diagram of an igloo can make it easier to explain the structure of an igloo:

All of these aspects take benefits of physics, so if it is -50◦C outside, the igloo can be warmed up to 20◦C

Must leave a ventilation whole, to avoid suffocation

Snow Holes

Igloos

What is a snow hole?

A snow hole, also known as a snow cave, is a hole dug in deep drifted snow. It is used as a temporary shelter, typically made for on purpose.

Why do people live in snow holes then?

Like mentioned before, snow holes are temporary shelter, mainly for mountain hikers that explore the cold parts of the world. Just like igloos snow holes are obviously a poor conductor of heat, so then why would people live in them? Well the benefit of a snow hole is when exploring places where there is a high amount of snow, the chances of having blizzards or getting stuck on a mountain at night is high, so therefore snow holes are useful to make.

Igloos and snow holes

What is an igloo?

An igloo is a type of shelter built out of out compressed snow. The snow blocks are harder than powdery snow and have trapped air bubbles which makes them poor conductors of heat.

So then why do people live in igloos?

Well, the idea of igloos is that the coldest air from the inside of the igloo runs downwards of the terrace.

The temperature inside an igloo is about 20 degrees.

Some experts say that a well-constructed igloo, coupled with a very small oil lamp and plain old body heat, can warm an igloo up to 40 degrees above the outside temperature.

Igloos and Snow holes are found in the coldest parts if the world, like ice lands. However igloos and snow holes are most common in Alaska.

Features of the igloos that make it warm:

CONDUCTION

Even though igloos are made up of ice, Eskimos manage to stay warm because their body heat warms the air surrounding the human body which eventually would increase the temperature because of the conduction, as our bodies gives out heat. Hot particles will vibrate quicker passing the heat energy to the other particles around it, and before u know it the whole igloo will become warmer. Both air and ice are good insulators and they reduce heat loss from inside the igloos to the surroundings by conduction.

Similar to igloos, snow holes have the disadvantage of being made out of snow. Snow is bad conductors so fires burnt in igloos won’t completely melt it. However snow holes are good insulators. Snow has air pockets in them which will insure that the igloo or snow hole is very well insulated. They trap the body heat, and in result it warms up the space. Snow also provides protection from the wind. A snow hole needs a ventilation hole, otherwise you would suffocate.

• Walls of igloos block the wind, which makes freezing temperatures feel many degrees warmer.
• Snow and ice work as insulators to trap body heat inside the igloo.
• A deep hole is dug at the entrance of the igloo, this will then act as a cold sink trapping cold air from the outside.
• Insulation abilities increase a few days after construction. Body heat and sun exposure cause the inside of the igloo to melt. When the igloo is unoccupied during hunting, the melted snow freezes over, turning into ice. Several days of melting and refreezing turns the entire structure to solid ice, making it not only unbreakable, but also warmer than ever.

CONVECTION

CONVECTION

The relatively hot particles will make the air less dense, so that the air is pushed up towards the top of the igloo. Cool air next to the igloo wall/roof will sink downwards. This is because the cool air which is sinking is denser than the hot air. So a convection circulation flow will be created inside the igloo.

RADIATION

Exactly the same for snow holes, the heat of the sun reflects off the white snow, so the ice does not melt. The ventilation hole located on the top is the main reason why snow holes don’t melt.

Since igloos are made of ice, and ice is white which reflects off heat. At the top of the igloo is a hole to allow ventilation. Hence called the ventilation hole. This is also the key reason why igloos don't melt. The hottest air and smoke rise up through the hole. The inside wall of the igloos blocks does melt, to some extent. But the outside air is so cold and the building blocks of snow are so thick that the blocks continually refreeze.

The ventilation hole on the top of the igloo allows air to enter

Features of snow holes that make it warm:

The raised sleeping platform is one of the warmest areas in an igloo.

• Snow Holes are made by digging thick show and making a hole. They are dug in the ground unlike igloos.
• Once cocooned within its icy walls you are totally protected from the elements, safe from wind, cold and storms.
• The temperature inside is the same as our body temperature, not only warmer, it's also quieter and safer, as a snow hole can't blow away.
• Snow holes an igloos are quite similar, they have the same insulation abilities, they melt and refreeze, making it stronger.

The tunnel is built below ground level

Cold air sinks and warm air rises

Thank you for listening and watching!