Submitted by SunCloud-777 t3_zy30z3 in todayilearned
Overall, the exchange of heat from a couple of people or even a smaller cooking/warming fire to the ice will be about the same or less than the loss of heat from the ice to the outside air. The best way to ensure that this is the case is to have a decent sized but still small opening at the top of the igloo (avoiding the centre because it would collapse). This lets excess smoke and heat rise out the top instead of possibly accumulating and causing slush and drips while still allowing for enough radiating heat from the fire to keep you warmer.
also the inside ices up. This prevents any warm air from penetrating the snow layer.
yes, from what i understand, a small vent is situated at the top of the igloo, plus bec it’s dome-shaped what little ice melt will flow down the side.
When we're talking about being "warmer" inside it could still be below freezing. If it's negative 20C and windy outside having a space that's 0C with no wind will feel way warmer.
Thats a good point. I guess -1ºC would feel comfortable without wind and with winter clothes when its windy and -15ºC outside.
Can confirm. I’ve slept in a snow cave a few times and it’s quite comfortable inside without the wind chill.
I’ve slept in a snow cave a few times in the pacific NW. It does in fact start to melt the snow a little bit, and I recommend making your snow cave a smooth arch on the ceiling. If you leave any pointy bits on the ceiling the melt water can drip down them and onto your sleeping bag. If it’s smooth any water will run down the side and now get you wet. It’s not enough melt to cause problems though. Just enough to melt the rough snow on the surface.
Outside temps were always between -5 and -10, so it may be different in the arctic or even just the interior where it gets colder than the coast.
Snow caves overall are quite comfortable though. The temp hovers around freezing, but since the air is so still it’s comfortable to take your shirt off and get changed.
water is a poor conductor of heat, meaning you have to put a lot of energy (heat) against it to heat it up (or cool it down). So, ice "wants to stay ice".
this is why ice cubes work so well to keep drinks cool.
so, if you think about how easy it is to heat air up, and compare that to water... your igloo example starts to make a little more sense.
It's wrong to say that water (or ice) is a poor conductor of heat because it takes a lot of energy to melt it. It's correct to say that water has a very high "heat of fusion" (latent heat involved in turning 0-degree ice into 0-degree water). Conductance refers to its ability to carry heat from a hot object on one side of it to a cold object on the other side. Snow (not ice) has very low conductance due to its large air content, the same reason house insulation works well; it has nothing to do with ice's high heat of fusion.
> Conductance refers to its ability to carry heat from a hot object on one side of it to a cold object on the other side
edit:
> It’s wrong to say that water (or ice) is a poor conductor of heat because it takes a lot of energy to melt it.
not what i said.
you basically said i was wrong, and then explained something else, said in other words.
i was trying to keep it simple. sure, it's not 100%. what i said is basically right, i explained in way that's easy to understand. unlike your explanation.
warm air inside the igloo does not conduct heat very well through the igloo material. if water was a better heat conductor, it would melt faster. many of the different thermodynamic properties are related to each other.
The reason it takes a lot of heat to change the temperature of water, or to cause a phase change from solid to liquid, or from liquid to gas, isn't because "water is a poor conductor of heat," but rather because "water has a high specific heat," which is the amount of energy (calories, BTUs, etc) needed to change a given weight of the material (one gram) by a given amount (one degree celsius).
This is what makes water pretty much the "ideal material" to use to transmit power in things like steam engines (turbine steam engines are still heavily used in power generation) or to carry heat in things like engine cooling systems or residential/commercial heating systems.
Water really has quite a few remarkable properties from a scientific or engineering standpoint.
>... you have to put a lot of energy (heat) against it to heat it up (or cool it down)
This refers to specific heat (energy required to change temperature) and is not the same as thermal conductivity.
>Ice wants to stay ice. this is why ice cubes work so well to keep drinks cool.
This refers to heat of fusion. Also not the same as thermal conductivity.
You could replace the ice in snow with different substances with lower specific heat, lower heat of fusion, and a melting point so high that melting is irrelevant, and it would still be a poor heat conductor due to the large air content.
every one of your comments in your comment history is argumentative, about stupid details and generally telling other people they are wrong.
you seem like a genuine asshole.
edit: omg that creep actually replied from an alt account just to get the last word in! hahahahaha
and every one of your replies in this thread is you being an argumentative asshole who also happens to be wrong half the time.
You were wrong though.. you said it was a poor conductor of heat since it takes a lot to heat it up….
Those are different things.
Its heat conductance isn’t amazing, but is not the same or well related to its specific-heat-capacity & the energy it takes to phase change…
None of that has much to do with igloos keeping warm largely by being a windbreaker & containing the air in the space… it anything.. its the conductivity of the air in the space that matters… and not the walls at all.
Water is an excellent conductor of heat, that's why it's so often used as a coolant.
The term they meant to use is "Heat Capacity".
Water has a high heat capacity; it takes a relatively high amount of heat (energy) to cause a change in temperature.
This is also why it makes a good coolant, as it can then transfer that heat.
this is really really wrong
water is not a good heat conductor, look it up.
edit: here's a link link
> In terms of heat conductivity, water is classified as a poor thermal conductor and acts as an insulator by resisting the flow of heat through it.
wow, this goes to show how much upvotes actually mean
I don’t think there’s an agreed upon definition of “good” conductors.
In an engineering context it’s a mediocre conductor and can’t compare to most metals, but in a wilderness survival context water is a very good conductor of heat and is to be avoided at all costs if you want to stay warm.
In practice it’s a better conductor than snow, rock, and any other material you’ll find since it’s a liquid (I know that’s not technically correct, but in practice it might as well be).
> I don’t think there’s an agreed upon definition of “good” conductors.
heat conductivity is measurable, and predictable link
The unit of thermal conductivity, k = J/s⋅m⋅C°
there's a table listing some materials.
one of the really unusual characteristics of water is its low heat conductivity, which is a basis of its importance for life on earth... if water conducted heat more, it would freeze faster, potentially also from the bottom up, and global temperatures might swing too fast to support life. the same goes for ice and it's unique characteristics.
Yes there is an element of heat capacity and other thermodynamic terms going on... but i was keeping it simple for the person i was commenting to. if someone doesn't know why an igloo doesn't melt, it's easier to explain with terms they might know better.
You didn't address a single thing I said. I'm aware that it's measurable and I don't need the physics lesson. Besides, you're not in any position to be lecturing anyone on thermodynamics.
i did address where you were flat out wrong, and then provided a scientific example as to why you were wrong. that you dismissed it, says all i need to know about this discussion with you.
"Good" is a subjective measure. No one has defined a cutoff point between good and bad conductors. You did not address that at all. I said that "in an engineering context it’s a mediocre conductor" and you just provided numbers that support that conclusion.
In the context of wilderness survival, you can eliminate most materials on those lists and compare its conductivity to rocks, snow, trees, bushes, grass, air, etc. Suddenly water is a very good conductor relative to the other materials you are likely to encounter.
wow dude, you just don't give up, huh. you picked a fight and your first sentence was wrong and you're back tracking.
"oh... well 'good' is a subjective measure"...
i said it was a bad heat conductor, and you took the opposite stance, and now you're trying to qualify your answer with completely different scenarios.
seriously man, i don't want to talk to you. this discussion happened yessssssterrrrday. you are a day 2 reddit twat that reads over comments and nitpicks them to death. ain't nobody got time for that.
I said the same thing in two different ways since you didn't understand the first time. That is not back tracking. If you don't want to discuss it you can stop replying any time.
This is wrong in at least four different ways:
Yeah! One time as a kid i brushed snow off my grandma's bush so it wouldn't die. My dad said the snow was actually keeping the bush warm and to just let nature do its thing. Lasted till now without me wiping off all the bushes, I guess 🤷
Glad you stopped brushing your grandma's bush
Ya'll behave yourselves 🤣
I legit laughed out loud. Well done.
kinda disrespectful to refer to grandma as "it"
Your dad was mostly right. Most all plants native to an area are native precisely because they are capable of handling the weather patterns.
In the US, there are weather zone planting guides that help determine if a tree or shrub would thrive where you live. If you want to plant something that will live as long as what your grandma planted, they are decent references.
You can sweat inside very well built igloos. I've read the insides can reach temperatures of up to 90 F, which doesn't make a whole lot of sense to me, but yet I can still sort of believe it.
You can build a fire inside them.
I’ve done winter camping and I can confirm, you can sweat inside snow shelters.
We didn’t make igloos, we made quinzees. The concept is similar, but instead of directly constructing a dome you just pile up snow as high as you can get it and then hollow out the center. After a weekend inside one, a thick layer of glassy ice built up on the inside. We were sometimes unable to knock them down when it was time to leave because the ice could withstand the weight of the 4 people who had lived inside jumping on top of it. The windchill was -40 that weekend and we had to remove layers once inside the quinzee.
Quinzees are amazing shelters and I do believe what most people mistaken think of when they hear 'igloo'. Igloos require specific snow and conditions to be able to build. Quinzees just require snow, preferably dense snow so it sticks together.
Just gotta be careful when building them. The whole idea is to have a shelter to protect against hypothermia, but if you work so hard you begin to sweat, you kinda defeat the purpose. Either requires a change of clothes or just take your time making one.
Yep, we were cautioned about sweating during training before our outing. Go slow, pay attention to your body, and remove layers (especially your hat, weirdly enough) if you get too warm. Sweat is deadly in the cold.
Snow is NOT an "excellent" insulator. It's a mediocre-at-best insulator. It has an average r value of 1. That's about the same as wood, which acts as a thermal bridge when it's next to an actual "excellent" insulator like fiberglass or even chopped up paper or leaves. The fact that snow insulates at all is wonderful and significant, but it's not particularly good at insulating.
You ruined OPs moment with the pain of thermo lol
(Fresh)
Yeah - what the hell is (fresh) supposed to mean or matter?
Freshly fallen - it will have a lot of air pockets like a down comfortor. If snow fell 2 weeks ago, it could have gone through temperature changes that caused it to melt a little and refreeze - compacting it and reducing all of the air pockets.
The air in the snow is fresh. Scented with lavender.
And why we shovel snow against our houses.
This can lead to leaks and water in the foundation/basement if you’re not careful
I've never heard of that.
But it does make sense.
I'm actually going to have to look into that.
Thanks!
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This was taught at my elementary schools in Colorado in the 70s/80s.
Each year, 5th and 6th grade students were taught winter survival skills such as how to build an igloo (and other shelters), signal for help, start a fire, etc.
My school didn’t. I’m bummed out now.
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And Snow is also an infoooorma! Summabummahumma, licky boom boom down.
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This is why in outdoor survival they teach you build a snow cave that will fit you and your sleeping bag and bivvy bag(body bag we called them), under at least 1-2 foot of snow for insulation. Ice the inside with a candle flame, it's much like building an igloo.
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When I was a kid, I went out walking in the woods behind my house after a big snowstorm and say a little bird, trapped in the snow, so I scooped out a hole for him.
So I guess I killed that bird.
It’s also incredibly quiet, probably because of this. Whenever it snows it’s eerily quiet, kinda like you’re in a sound booth
Snow absorbs sound waves a lot better than open ground.
Legitimate question: Then why is it when snowfall ends up piled up against a house/windows the house is noticeably colder? Shouldn't it help insulate the house further and keep it more warm?
Where I live, we have winter snow for at least five months. I cannot say that I have noticed that issue where I live. houses here feel colder in the winter because it is colder outside. People tend to not pile snow up against their homes because they don’t want extra water in the spring to intrude into the basement. The homes where I live are typically insulated well enough that snow piled up would not really affect the temperatures of a home. I suppose that snow piled up against the house would block solar heat gain during the daytime.
Tell that to Elon Musk. He mentioned using the tesla solar panels to heat up your roof...during winter....the season with the least sunlight.
What did the suspicious husband say after he caught his wife cheating inside his igloo?
"Inuit!"
Meh.
heh
RobleViejo t1_j23kray wrote
I knew this, but I still don't understand why they don't melt over. If snow is a good insulator, and the inside is above 0ªC, then why doesn't it melt? I suspect the snow reaches a balance between the outside and the inside that keeps its integrity, but shouldn't igloos drip water from their ceiling?
There is also a famous "Ice Hotel" made completely from ice. I remember watching people walk around inside it fairly light dressed and yet there wasnt any water at all.