Name: How An Igloo Keeps You Warm
Uploaded: 2017-10-17T17:58:27.000Z
Duration: 5 min 17 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

For thousands of years, humans, and plants and animals long before that, have been using

No one knows for sure who built the first igloo, but with the right fit and the right

physics, snow can actually warm you better than the inside of a tauntaun.

So, how can something cold keep you cozy?

The vast, frozen Arctic is one of the most forbidding environments on our planet, yet,

the Inuit have managed to live there for about 5,000 years.

Out on the pack ice, winter temperatures reach 50 degrees below zero , and when it’s that

It’s not an area known for its forests, so nomadic hunters learned to build with the

Eskimo languages really do have dozens and dozens of different words for snow, because

there are a lot of different types, and the type of snow you choose can dictate whether

your igloo keeps you warm, or turns you into a Homo sapiensicle.

To understand this, we need to know a little something about being cold.

When your body temperature starts to plummet – you’re feeling heat leave you.

Cold can’t move into your body – in fact, there is no such thing as cold.

Think of heat as an actual quantity of stuff:.

The more you give away, the colder you feel.

This trading of heat can happen three different ways: by convection, conduction, and radiation.

A person inside will radiate body heat, which moves around the igloo by convection, and

This is exactly what happens in your house.

Fatty tissues like blubber help stop heat transfer in whales and seals, but for animals

who don’t have as much junk in the trunk, they cover themselves in air.

Sea otter fur, for example, is about a thousand times denser than human hair.

It’s snuggly stuff "This is the softest thing I've ever felt

You are adorable!" …but the secret to its insulation power

Otter fur is spiky, so it traps insulating air molecules.

Powdery, fresh snow can be up to 95% trapped air.

This makes it an excellent insulator, but the same way you have to pack it in your hands

to make a snowball, it isn’t dense enough to build with.

Solid ice, on the other hand, makes a good windbreaker, but it’s too heavy to lift.

Inuit hunters took the Goldilocks approach: the secret to good igloo snow is somewhere

Traditional igloo blocks aren’t molded, they’re cut out of the ground.

That tightly-packed ground snow is dense enough to hold up, but because it still has far more

air pockets than a block of ice, it’s light, and still a pretty good insulator.

As usual, animals figured this one out long before humans.

Polar bears, groundhogs, even birds like grouse all make snow burrows to stay warm.

And even before that, plants were tucking into snow to avoid death by freezing.

During the warm months, heat energy from the sun builds up in soil, and just like the the

roof above your head, a deep covering of snow prevents that heat from escaping onward and

This snowy blanket above stops ice crystals from forming inside plant roots, and shoots,

Not freezing to death is a pretty good motivator for any animal to get crafty, but our big

primate brains took it one step further with igloos.

Their engineering maximizes warmth and stability.

Cartoon igloos look like flat-bottomed half-spheres, but in reality, they’re neither of those

If you were to slice a real igloo in half, you’d see a shape called a catenary.

This gradually sloping shape is the same one that would form if you held a chain from both

A catenary arch distributes weight more evenly than a half circle, without bulging or buckling.

In fact it’s one of the most stable arches in nature, so sound that we still use it today.

Inside, snow houses are carved in different levels.

The hot air rises, and the cold air sinks down into the lower part, and away from where

To boot, body heat melts the innermost layer of the walls, strengthening the barrier between

you, your airy snow-block insulation, and the frigid great beyond.

When you live in an igloo, you act as a living furnace.

Over time, the temperature in your icy abode can hover some 40-60 degrees above the surrounding

air, but bring a friend to your igloo party, and you’ll get warmer, faster.

"Hey, you remember that thing I said about eskimos having all those different words for

Well our friends from Idea Channel made a video about that.

Here's an idea, you should go check it out.