What my son likes the most with winter is making a snowman.

What my son hates the most with winter is melting of his snowman.

I really would like to make him happy and make the snowman survive for as long as possible.

By the way, I am a king, with a medieval-level technology. My castle is in a temperate climate - think something like middle of France - quite far from the sea.

I already have caves and catacombs where it's quite cold, but I could build a specific building if needed.

There is no magic or alchemist involved, only snow. There is magic in my universe, but a realistic solution would be better.

What can I do to make my son's snowman survive, using medieval technology?

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    Recommended song to listen while reading / answering this question: "Do you want to build a snowman?" from Frozen :) – Pavel Janicek Aug 13 at 12:19
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    Just a thought, the thing he likes the most is building a snowman. By giving him an "everlasting" snowman the joy is then taken away... Sure he never has to suffer again but he will not need or have space to build more than a few. Joy and Suffering are a cycle, one without the other is meaningless... – BMS21 Aug 13 at 12:27
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    @BMS21 Your answer is logically meaningless. People might notice joy and suffering more if they experience the opposite emotion to compare them to, but joy can exist without suffering, and suffering can exist without joy. The saying that one can't have joy without suffering is just sour grapes, said by humans who live in primitive backwards societies - like Earth in the 21st century for example - filled with suffering, to make their misery seem more endurable. – M. A. Golding Aug 13 at 20:01
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    You are probably wise to avoid the alchemical route. The synthesis path for Sodium polyacrylate (artificial snow) does appear to consist of steps and materials that would be readily available to a mediaeval alchemist, but the process involves the creation of things like nitrobenzene which is both extremely volatile and extremely poisonous, and many of the reactions are substantially exothermic and must be carefully controlled lest the explosion remove the alchemist's lab from your castle's tower... Especially if you're making sufficient quantity for a snowman. – Perkins Aug 14 at 1:23
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    @BurnsBA With evaporative cooling (in air) you can't reach temperatures below the inlet temperature of your evaporating liquid. – Jan Doggen Aug 14 at 7:55

11 Answers 11

Use your caves or catacombs to make ice cellars. Their history goes back to 1780 BC.

enter image description hereSource: Early Ice Houses)

Use ice if you can find it, otherwise pack the snow as dense as possible.

See also this question on History SE.

Finally, tell your son to build the snow man inside.

Just try this - even if I'm not sure if this answer fits your "no alchemy" point: Before building the snowman just mix some sawdust into the snow, the finer the better. This will effectively prolong the life of the snowman significantly without the need to build any extra buildings or the like.

See https://en.wikipedia.org/wiki/Pykrete for a sample.

P.S.: I would love to post any original sources here, but I can't seem to find any on the run which don't just coat the snowman in sawdust, not mixing the snow beforehand. But nevertheless this works just fine and lets your snowman stand in the open up until the sunny May or June.

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    So... alchemy didn't always include spoons? – NotATyrant Aug 13 at 22:32
  • This combined with Jan Doggen's ice cellars would probably work extremely well. – David K Aug 14 at 14:04

You could convert the water deposit of your main city in an ice cellar.

They were insulated with sand, straw, sawdust, but the water cisterns even made it colder. Imagine something like this full of water (this was the medieval cistern for a city with 30,000 people)

enter image description here

  • What city was this picture from? – Elysian Fields Aug 15 at 12:28
  • @ElysianFields Lérida (Spain), ~165 km (100 miles) from Barcelona. That cistern is quite beautiful and, being underground, it has an impressive size. – Alberto Yagos Aug 15 at 13:04
  1. Find high enough mountain
  2. Get snowman above snow line

For the reference, Alps have snow line at around 2,5-3 km..

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    Man.. such a simple out-of-the-box solution. – pipe Aug 14 at 7:55

In the region where I have grown up, they used to harvest snow during winter from nearby mountains and store it in underground rooms insulated with straw.

Therefore:

  • Build a large underground room, so that it is protected from the day heath.

  • Fill it with snow and straw, add salt for further cooling

  • let your son make the snowman, wearing a good woolen coat

  • give the snowman a woolen coat, too (yes, wool insulates from thermal exchanges in both directions...)

In 400BCE, Persia had special structures that collected water in the winter, turned it into ice, and kept it cold for the entire summer:

See: http://en.wikipedia.org/wiki/Yakhchāl And: http://www.ccsenet.org/journal/index.php/ach/article/view/13822/12244

Yakhchāl (Persian: یخچال‎‎ "ice pit"; yakh meaning "ice" and chāl meaning "pit") is an ancient type of evaporative cooler. Above ground, the structure had a domed shape, but had a subterranean storage space; it was often used to store ice, but sometimes was used to store food as well. The subterranean space coupled with the thick heat-resistant construction material insulated the storage space year round. These structures were mainly built and used in Persia. Many that were built hundreds of years ago remain standing.

By 400 BCE, Persian engineers had mastered the technique of using yakhchāls to create ice in the winter and store it in the summer in the desert. In most yakhchāls, the ice is created by itself during the cold seasons of the year; the water is channeled from the qanat (Iranian aqueduct) to the yakhchāl and it freezes upon resting inside the structure.

Put the snow man in a cooling bath with some salt in it.

Salts like ammonium chloride lower the melting point of water-ice solutions: "−10 °C can be achieved with a 1 to 2.5 ratio by weight of calcium chloride hexahydrate to ice.".

That should keep the snow man cool. You would need a natural deposit of that salt (probably a different salt than just sodium chloride). Mining will probably help there, because many million years ago there may have been sea where now is middle of France.

The knowledge of cooling by adding salt crystals to water would probably be something in the realm of an alchemist, but once somebody (a traveling alchemist) told you, the way to maintain a cooling bath would be rather simple (just keep on adding special salt crystals and change the mixture often).

Example setup: https://www.thoughtco.com/create-a-safe-endothermic-chemical-reaction-602207

See also about Frigorific mixtures.

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    I think you have misunderstood: this does not keep heat away. It does not create cold. – MichaelK Aug 14 at 9:36
  • @MichaelK I think I may misunderstand you. How does using a cooling bath with salt in it, having a temperature below zero, not create cold and keeping the heat away? Isn't there thermal convection taking place? – Trilarion Aug 14 at 11:38
  • You could just as well surround the snowman in a shell of snow with a(n original) temperature of -20°C. The salt makes no difference. The thing here is you have to keep heat away from the snowman, i.e. insulate it from heat. You can do that in two ways: 1) something that block heat from reaching it, i.e. an insulation layer 2) something that soaks heat (i.e.a heat sink) that you can then replace continuously. Your solution does not do that better or worse than anything else. – MichaelK Aug 14 at 11:45
  • @MichaelK Yes, the salt indeed makes a difference. Dissolving salt crystals is an endothermic reaction, meaning it takes away additional heat and works different from snow because it only needs water. Read for example: thoughtco.com/endothermic-reaction-examples-608179 or en.wikipedia.org/wiki/Endothermic_process It really works. Whether it works better or worse probably depends on the technical circumstances. – Trilarion Aug 14 at 11:49
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    Ok, I stand corrected. You are talking about mixing ice and salt, which forms a frigorific mixture. The most you can achieve with that is -18°C, which is indeed impressive. But it needs to be ice and salt that you mix. Liquid water and salt will not yield any temperature drop. So: you still need to keep superfluous snow/ice around. What you are doing with the salt is simply to extend the time you can use one batch of snow. – MichaelK Aug 14 at 12:02

As a bare minimum, you should take a sprayer with water (or just broom/bossom; or even a bucket of water — depending on the snowman's size) and cover the snowman's surface. Of course, it should be relatively cold outside (so that water soon/immediately freezes). This may deform snowman's surface a bit, but probably will make the snowman somewhat more secure against temporary warmings.

Sorry, if the advice is too obvious.

Update: Per Nathan Cooper, it might be just a myth/mispractice/rumor that covering a snowman with a layer of ice would strengthen it against warmness. Thermal conductivity of ice is actually higher and albedo of ice is actually lower. Or this procedure (covering a snowman with a layer of ice) may serve some specific goals (like durability of small details against wind), but not the warmness-protection.

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    Why? Ice has a higher thermal conductivity and reflects less sunlight as snow. What are the advantages here? – Nathan Cooper Aug 13 at 14:41
  • @NathanCooper, I don't know what are benefits from theoretical point of view, but I sometimes heard that people do it in practice (through I never did it myself). To say truth, I am now not even sure that it's intended to protect from warm, maybe it was intended to protect small/loose details from wind. Or is it just a mispractice that passes from ears to ears? – Sasha Aug 13 at 15:23
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    I actually have no idea. Tone doesn't come across in text, but I'm legitimately curious, because I think I may have heard that advice before as well. I know that you should cover ice blocks with snow, but that's different. I would test it, but I'm short on snowy weather atm. – Nathan Cooper Aug 13 at 19:25
  • Solid ice is denser? Takes longer to melt? Igloos are made from compacted snow, not ice blocks. – can-ned_food Aug 13 at 20:13
  • When I was young I was told (perhaps incorrectly) that you do this to igloos -- maybe to make them stronger e.g. harder (assuming e.g. in winter that it's already more than cold enough). – ChrisW Aug 13 at 20:59

In addition to the cold-room solutions proposed by others, get your son to mix the snow with sawdust as he makes the snowman.

This will drastically increase the snowman's resistance to temperatures and melting by making a mixture known as Pykrete.

As an added benefit it's also much more resistant to physical damage, in case any pesky peasants attempt to destroy it.

Step 1. Dig a ditch around the snowman. (So the snowman can't run away)

Step 2. Tie a rope around the ditch and pull until the snowman and ground under the snowman moves.

Step 3. Pull the snowman and ground under it to the North or South poll.

Step 4. Take your son there and hope that he won't get lonely with just the snowman to talk to.

Make a bell-shaped glass container, one for each snowman. Then with the aid of a little magic have a dragon suck all the air out of it in order to create a vacuum. A little more magic is needed to seal it. Then, similarly to interstellar space, thanks to the absence of particles that could transmit heat to the snowman, it should take quite long to melt. Keep it in the shadow, you never know.

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    A vacuum makes the problem even worse. A vacuum causes ice to sublimate into vapor. On top of that, the vacuum will not do anything to prevent heating via conduction, through the base, and radiation, through the glass walls. You need construction like a Dewar. – user71659 Aug 13 at 16:22
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    As the other guy said, you should look at a phase diagram for water. Phase diagrams show the most stable physical forms — solid, liquid, gas — of a chemical at certain measured temperatures and pressures. – can-ned_food Aug 13 at 20:19
  • Very nice, thanks for the interesting feedback! ;-) – Will Aug 14 at 6:56

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