How exactly does a dragon's cold breath weapon work?

[gooddragon1]

Preface: I have no problem with cat girls. Some of my favorite anime characters are cat girls.

So, how would a dragon's cold breath weapon work? I've heard some theories that it takes the heat out of the air. Would it be a substance? Could it be a type of energy that counters thermal energy? What sort of physics involved (or otherwise) answers can you think up?

Cat girls deleted my WoW character. Whether or not this was intentional makes no difference to me.

[Lorsa]

Why are you interested in a Dragon's cold breath in particular? D&D holds so many fantastic and magical things it makes me curious about the motivation behind this.

The answer is: you have to ask whoever placed Dragons in the D&D Monsters Manual. Nobody knows the physics of D&D really.

[veti]

I've always imagined it as, simply, a breath of extremely cold air. Like air conditioning turned up to 11. Cold enough to freeze small volumes of water. As to how, exactly, the dragon produces such a thing - well, in much the same way as other dragons produce fire, I guess.

[Fri]

Evocation school of magic exist. you can evoke (or disappear) energy out of nowhere in DnD.

Elemental planes exist, one of them is elemental plane of ice. You can conjure things out of it, cold ice cubes included.

[Karnack]

A dragon's lungs are charged with elemental energy from an organ in has next to the heart called the draconis fundamentum. It then projects said elemental energy from it's lungs when it uses the breath weapon. In the case of cold breath weapons you may notice this does not follow the laws of thermodynamics. This is because it's magic and it ain't got time for science, it's too busy being awesome.

[ThinkMinty]

It's the magic equivalent of liquid nitrogen. So cold it HURTS.

[Takewo]

They were fire dragons, but cat girls broke their hearts and now they are as cold as ice, their breath weapon is simply the defrosting feature.

[Lorsa]

It's the magic equivalent of liquid nitrogen. So cold it HURTS.

This is bad. Now I wonder how much liquid nitrogen actually hurts. I mean, I haven't tried, have you?

To be honest, liquid H20 also hurts at some temperatures (well, it hurts at a lot of temperatures really, but in two different ways).

I don't think it has so much to do with actual temperature as its ability to effectively steal heat from your body.

[Storm_Of_Snow]

It's the magic equivalent of liquid nitrogen. So cold it HURTS.

More like so cold it instantly freezes the water in the cells of your body, causing them to rupture, solidifies the blood in your veins, so that your circulation fails and your extremities suffer oxygen deprivation and die, and reduces the reaction rates of the enzymes in your body so that your metabolic processes shut down and your body is unable to sustain itself.

The pain comes later, and then only if your nerves defrost enough for you to be able to feel it.

[Yuki Akuma]

In D&D, it works exactly the same way as Cold energy spells work, because it's also literally magic.

I can't think of any other settings with dragons that breathe cold. Elder Scrolls, I guess? In which case... same answer.

This is bad. Now I wonder how much liquid nitrogen actually hurts. I mean, I haven't tried, have you?

Incidental contact with liquid nitrogen doesn't hurt. It evaporates more or less instantly and is kept away from the surface of your skin in the same way water floats above the surface of a really hot pan. At worst you might get a little chilly if you spill some on your hand. Getting it soaked into your clothes is bad, because then it sticks around to keep leaching heat out of you, but you can get out of your clothes fast enough that it won't do anything major.

Full immersion in liquid nitrogen for more than a few seconds will freeze the water in your cells and cause severe frostbite, which hurts like hell, and can lead to major necrosis, so don't do that.

[gooddragon1]

I liked the idea of air conditioning until I turned it up to an arbitrarily large number in my head. If you chill air to a low enough temperature it will become a liquid and then a solid.

Why are you interested in a Dragon's cold breath in particular? D&D holds so many fantastic and magical things it makes me curious about the motivation behind this.

I can almost guarantee that it has nothing to do with my profile pic whatsoever.

On second thought, I don't like how that sounds (it doesn't feel nice): it's because of my profile pic.

[Lorsa]

I can almost guarantee that it has nothing to do with my profile pic whatsoever.

Ok. I'm glad we cleared that up.

(the above is also sarcasm btw)

Incidental contact with liquid nitrogen doesn't hurt. It evaporates more or less instantly and is kept away from the surface of your skin in the same way water floats above the surface of a really hot pan. At worst you might get a little chilly if you spill some on your hand. Getting it soaked into your clothes is bad, because then it sticks around to keep leaching heat out of you, but you can get out of your clothes fast enough that it won't do anything major.

Full immersion in liquid nitrogen for more than a few seconds will freeze the water in your cells and cause severe frostbite, which hurts like hell, and can lead to major necrosis, so don't do that.

I'm curious how I could accomplish full immersion in liquid nitrogen. I mean, if it was a bathtub full of it, chances are the room would contain almost exclusively N2 anyway, making it somewhat hard to breathe. If you spill out a high-pressure bottle of liquid N2 in an elevator, it's not the cold that will kill you, it's the resulting lack of oxygen.

[Storm_Of_Snow]

Incidental contact with liquid nitrogen doesn't hurt. It evaporates more or less instantly and is kept away from the surface of your skin in the same way water floats above the surface of a really hot pan. At worst you might get a little chilly if you spill some on your hand. Getting it soaked into your clothes is bad, because then it sticks around to keep leaching heat out of you, but you can get out of your clothes fast enough that it won't do anything major.

Full immersion in liquid nitrogen for more than a few seconds will freeze the water in your cells and cause severe frostbite, which hurts like hell, and can lead to major necrosis, so don't do that.

There's the trick of dipping a flower into liquid Nitrogen for a few seconds, then pulling it out and smashing it with a hammer.

And there was also the craze a few years back for bars to use liquid Nitrogen in drinks to make them form a fog from it, and the woman who didn't wait for it to boil off (and she wasn't told, and the bar got heavily fined IIRC), and wound up having her stomach and lower oesophagus removed (although mostly because the gas expanded and split her stomach open rather than from the effect of the cold).

[Brother Oni]

I'm curious how I could accomplish full immersion in liquid nitrogen. I mean, if it was a bathtub full of it, chances are the room would contain almost exclusively N2 anyway, making it somewhat hard to breathe. If you spill out a high-pressure bottle of liquid N2 in an elevator, it's not the cold that will kill you, it's the resulting lack of oxygen.

Large quantities of liquid nitrogen don't evaporate that quickly (it's complex) and you'd be more than able to jump into a bathtub of liquid nitrogen if freshly poured - by the time the room's O₂ had been completely displaced, the bathtub would probably be empty.

That said, the O₂ concentration being displaced to dangerous (sub 19%) would happen far more quickly but I don't have time at the moment to crunch the numbers.

[Lorsa]

Large quantities of liquid nitrogen don't evaporate that quickly (it's complex) and you'd be more than able to jump into a bathtub of liquid nitrogen if freshly poured - by the time the room's O₂ had been completely displaced, the bathtub would probably be empty.

That said, the O₂ concentration being displaced to dangerous (sub 19%) would happen far more quickly but I don't have time at the moment to crunch the numbers.

Yeah, I do realize that "almost exclusively N2" was a bit of an overstatement. In any case, I mostly wanted to highlight that there are other considerations regarding liquid nitrogen than just the cold.

I don't think the numbercrunching is necessary unless any of us feel the need to take the nitrogen bath.

I guess liquid nitrogen is more "safe" in the oxygen displacement department than a regular high-pressure N2 gas tube. As you said, it takes a while for it to evaporate.

[goto124]

How likely is a dragon able to toss out liquid nitrogen? Makes a bit more sense for a sci-fi dragon robot, maybe?

[Storm_Of_Snow]

How likely is a dragon able to toss out liquid nitrogen? Makes a bit more sense for a sci-fi dragon robot, maybe?

If it can chill it down to about -200C, it's perfectly possible. Liquid CO2 at -57C's more likely though, with the rest of the visible effect being frozen water vapour.

[Darth Tom]

I always kind of assumed Cold Dragons are cryogenic, and their breath weapon is a liquid helium quench. Those can certainly be nasty enough to freeze a bunch of people wearing nice conductive metal armour.

Why are they cryogenic? I don't know. Our body core temperature is different from that of, say, a fish, (I think), so surely in a high magic environment just going a little further is reasonable. OK it's on the order of ~300K, but nonetheless its the same principle right?

[Brother Oni]

If it can chill it down to about -200C, it's perfectly possible. Liquid CO2 at -57C's more likely though, with the rest of the visible effect being frozen water vapour.

There's a video on Liveleak of a pool party where the organisers decided to go for an atmospheric fog effect by pouring large quantities of liquid nitrogen into the pool with people in it (they had quite a few 10L dewars). It didn't end well.

Presumably there's an optimal temperature range where the liquid is still cold enough to cause damage, but the temperature differential to the target isn't sufficient to cause the Leidenfrost effect (the aforementioned reason why incidental contact of liquid nitrogen isn't harmful) on incidental contact.

[goto124]

And there was also the craze a few years back for bars to use liquid Nitrogen in drinks to make them form a fog from it, and the woman who didn't wait for it to boil off (and she wasn't told, and the bar got heavily fined IIRC), and wound up having her stomach and lower oesophagus removed (although mostly because the gas expanded and split her stomach open rather than from the effect of the cold).

There's a video on Liveleak of a pool party where the organisers decided to go for an atmospheric fog effect by pouring large quantities of liquid nitrogen into the pool with people in it (they had quite a few 10L dewars). It didn't end well.

Are frost dragons just human-created liquid nitrogen dragon robots that went out of control?

GNO GNOMES! Oh wait...

[Joe the Rat]

Enh. It's just sound waves.

Cold-breath dragons produce a hypersonic roar in a focused cone that works at the vibrational frequencies of water molecules - specifically in counter vibration, so it reduces molecular motion, making the water vapor in the air, and by extension the air itself colder. Really powerful dragons can shift to N2, letting them freeze things in a desert.

[gooddragon1]

Enh. It's just sound waves.

Cold-breath dragons produce a hypersonic roar in a focused cone that works at the vibrational frequencies of water molecules - specifically in counter vibration, so it reduces molecular motion, making the water vapor in the air, and by extension the air itself colder. Really powerful dragons can shift to N2, letting them freeze things in a desert.

How about a counter vibration that adjusts for all matter and perhaps even energy rather than just air molecules?

[JAL_1138]

Dragons that breathe "acid" (used incorrectly as a catchall term for corrosive chemicals) use the same principle as bombardier beetles--they have two sacs, each with a different chemical (that's harmless to the dragon (and indeed on its own), that when combined produce an extremely caustic compound. Each chemical is aerosolized by both the force with which it is expelled through a small orifice within in the dragon's mouth, and the dragon's exhalation of air, and combine to form the caustic compound a short distance past the dragon's mouth.

Dragons that breathe fire have the same structures, but the chemicals in the sacs, when expelled, combine and produce a strongly-exothermic reaction instead of forming a corrosive compound.

Dragons that breathe cold, same thing except they have chemicals that produce a strongly endothermic reaction.

Dragons that breathe poison (actually venom, but D&D and colloquial English have always been bad at that distinction) simply have venom in the sacs, expelled and aerosolized by the same method as the others.

The real question is how in blazes the dragons that breathe lightning work. Presumably with an organ similar to that of an electric eel, although that doesn't explain how they're able to direct it in a line. Perhaps some sort of guided plasma-channel?

[Psyren]

How about a counter vibration that adjusts for all matter and perhaps even energy rather than just air molecules?

All you need for that is to alter the pitch/resonance, so yeah.

But the real answer (which was already stated, and doesn't contradict the above either) is that yes, they are breathing out a substance - really, really cold air.

[Kelb_Panthera]

If you're looking for an answer that fits with modern physics, don't. It's not there to find.

D&D physics works on a classical, four elements model of reality. Cold is not the absence of heat but a confluence of elemental air and water. That's what's coming out of the white or silver dragon's mouth just like the elemental fire of a red or gold dragon or the confluence of air and fire that is a blue dragon's lightning breath.

It's either accept the above, or learn about quantum physics and exotic particles and energies. Some kind of carrier particle that inhibits molecular interaction is pretty much the only thing in modern physics that could explain "cold energy" and then you have the fun of trying to figure out how an organic body could produce such an effect. Good luck.

[TheThan]

I figured it's just a really, really big breath mint.

[gooddragon1]

Dragons that breathe "acid" (used incorrectly as a catchall term for corrosive chemicals) use the same principle as bombardier beetles--they have two sacs, each with a different chemical (that's harmless to the dragon (and indeed on its own), that when combined produce an extremely caustic compound. Each chemical is aerosolized by both the force with which it is expelled through a small orifice within in the dragon's mouth, and the dragon's exhalation of air, and combine to form the caustic compound a short distance past the dragon's mouth.

Dragons that breathe fire have the same structures, but the chemicals in the sacs, when expelled, combine and produce a strongly-exothermic reaction instead of forming a corrosive compound.

Dragons that breathe cold, same thing except they have chemicals that produce a strongly endothermic reaction.

Dragons that breathe poison (actually venom, but D&D and colloquial English have always been bad at that distinction) simply have venom in the sacs, expelled and aerosolized by the same method as the others.

The real question is how in blazes the dragons that breathe lightning work. Presumably with an organ similar to that of an electric eel, although that doesn't explain how they're able to direct it in a line. Perhaps some sort of guided plasma-channel?

Toss up between this one and the counter vibration one. Slightly in favor of the counter vibrations because it doesn't involve stored matter.

[Âmesang]

I just sort of pictured cold breath weapon attacks resembling a super-cooled snow blower attack, at least with regards to appearance. Perhaps resembling Sub-Zero's ice blasts from Mortal Kombat:
https://www.youtube.com/watch?v=fEYibbsDvAw

The real question is how in blazes the dragons that breathe lightning work.

POWER! UN-LIM-I-TED POWER!!

For the longest time I didn't know what he was saying until I turned on the subtitles.

[Knaight]

An obvious possibility is just an extremely endothermic chemical reaction, where an aerosol spray is used to distribute the particles, which then stick to surfaces and react, leeching heat from the surfaces themselves. A similar possibility would be a gas expansion which cools the gas as it expands, which is a property of a number of real substances within certain temperature/pressure ranges. For a lot of these it isn't too dramatic a change, but that isn't a big deal.

If you look at the nitrogen curve in particular, you'll see that there's a cooling process within any reasonable temperature, up to pretty ridiculous pressures. So, the dragon breathes in a huge quantity of air, pressurizing it with a biological pump as they do so. The dragon itself avoids heating up during the compression process by sweating, getting it a large amount of compressed gas. Then, it breaths out, throttling as it does so. That gets a cold gas, and it can also remain at pretty high pressures and thus high densities. High density gases traveling quickly have very high convection heat coefficients, so it will cool anything in the area extremely quickly. Thus, cold damage.

[Cluedrew]

The real question is how in blazes the dragons that breathe lightning work. Presumably with an organ similar to that of an electric eel, although that doesn't explain how they're able to direct it in a line. Perhaps some sort of guided plasma-channel?

If I remember BIO 347 correctly they have a pair of sacs like the others except the sacs have a highly uneven lining (like your intestine). As the liquid in the sacs sloshes around they become ionized, that is positively and negatively charged. Unlike the other dragons they expel liquids from these sacs one after the other. One (I believe the positively charged one) in a stream for a fraction of a second. Then they release the other in a burst, the positive negative charges cancel and a they do the moving voltage creates "lightning" along the initial stream. Also, I never actually took BIO 347 and if I did I don't think they would have talked about this.