How can people have fires inside igloos without them melting through the ice?

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In: Chemistry

14 Answers

Anonymous 0 Comments

What happens is the rough inside later of the igloo melts a little bit at first but the super cold ice behind it which is being kept cold by the outside temperatures freezes it again in to a smooth crust. Because there’s now less surface area the warm inside air is less effective at melting the surrounding ice.

So basically it’s a constant battle between the fire inside warming up the air and the ice and cold air keeping the structure frozen, and the achieve a balance at some point.

Anonymous 0 Comments

I learned how hard it is to melt snow/ice with fire in an interesting way. My boss told me to we had a “parade” of higher ups coming through. There was a bunch of dirty snow in the parking lot. I went to Home Depot and rented the biggest kerosene heater I could. Had guys pack it up high and pointed it right at the base. Maybe an hour later very little progress.

One of the guys who reported up through me walked by, called me a dumb fuck and said that’s going to take forever. It was 60 degrees out and he grabbed 2 guys and they broke it up and threw it in a thin layer over the parking lot. Took like 2 hours to melt on its own after that. It would have taken us a day to melt it all.

Anyway, getting schooled by a technician was fun. Little did he know I just wanted to play with a kerosene heater. But, he did get to call me dumb which was a positive for him and taught me a lesson on how many BTU’s it takes to phase change ice to water.

Anonymous 0 Comments

Igloos often have a small hole in the side and one on top. The side hole allows fresh air while the top hole allows CO and smoke to leave. Much of the heat also leaves through that hole.

Anonymous 0 Comments

Snow with an ice layer over it is very insulative. That keeps the heat inside and the cold out. It also keeps the heat out of the actual snow and the ice sort of keeps itself cool. It is the same reason that snow that has a crust of ice takes so long to melt even if it is way above freezing.

Anonymous 0 Comments

They say if you ever get stuck in a car in the middle of winter, a tealight candle on the dashboard can provide enough heat to get you through the night.

Anonymous 0 Comments

Not an igloo expert, but am firefighter trainee.

Fire science is… wild. The stuff you learn in high school chemistry doesn’t hold a candle(eyyy) to the real thing.

Heat wants to rise and so does fire. You know how they always say close doors and windows to contain a structure fire, and how modern buildings have actual fire doors? Basically what this does is contain a fire until help arrives. It’s not going to put it out.

What firefighters do in a fully involved fire is the exact opposite. They vent the roof directly above the hottest part of the blaze. This causes both smoke and heat to escape vertically so that a fire attack team can enter from the side and extinguish the fire without being melted. Turnout gear and water vapor alone have their limits.

In addition, water doesn’t magically extinguish fire, as you can see from oil fires burning on water. Water only cools the fire’s fuel below its ignition point and thus puts it out.

So I’d imagine with the igloo scenario, enough heat escapes vertically that the interior is warmed without melting the ice, and the cooling effect of the outside air on the ice keeps it in a solid state. I’m sure many igloos have melted from too much fire and too small a chimney.

Anonymous 0 Comments

https://howeverythingworks.org/1997/01/10/question-730/#:~:text=But%20while%20a%20central%20fire,and%20it%20won’t%20melt.

To avoid melting the ice, people must keep the ice below its melting temperature. That means that they can’t add heat to ice indefinitely. But while a central fire will always deliver some heat to the ice of the igloo, the ice of the igloo will also tend to lose heat to colder air outside.

As long as the ice loses heat at least as fast as the fire delivers heat to it, the ice won’t become any warmer and it won’t melt. Water has a lot of latent heat. This means that it requires a lot of energy to transform water from ice to liquid, even though the temperature stays at 0°C.

Furthermore, water has a high specific heat capacity, which means it takes a lot of energy to change the temperature at all. And finally, even though the air inside is maybe ~10°C, the outside might be waaay below 0°C, and might might be windy, causing the equilibrium temperature of the ice to be well below 0.

Anonymous 0 Comments

An important note is that the goal of warming the inside of the igloo is NOT to keep the inside a temperature that you would be comfortable in your home. It is to make it more comfortable in clothes and blankets. The structure does melt if the internal temperatures get too high. As others have said, you want to find an equilibrium so that the melting is not happening faster than refreezing. If you want the structure to last more than a few days, the internal temperature needs to be fairly low, say 40s or perhaps up to 50s. This is a welcomed respite from negative temperatures in the arctic.

Snow melt, humidity from your body, and breath will freeze into the cracks, helping to seal the structure and block wind and the elements from infiltrating. However, ice is a much worse insulator than the packed snow initially used to create the igloo, so you don’t want the walls to too thick with ice. The ice also helps trap moisture inside, thus increasing the relative humidity inside of the igloo. Super cold air is very dry, and can make it painful to even breathe. Humid air also holds heat better than dry, so a small heat source can provide a better warming effect when the humidity is slightly higher.

Anonymous 0 Comments

I also always wondered how they are ventilated?

Anonymous 0 Comments

It looks like your question was mostly answered. I would add that another good example is that ice fisherman who are out on the ice for the day (not in a fishing shanty) sometimes start a fire on the ice for warming up and cooking. The ice melts a little and then a layer of cold water battles with the fire on one side and the ice on the other (very similar to the layer inside the igloo). Even after a full day of fire, it will only melt a few inches into the ice.