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View Full Version : Does cold damage freeze water? [3.5]



gomipile
2010-08-16, 07:09 PM
For roleplaying reasons, I'd like my next sorcerer to be able to create a bit of ice for people's drinks by casting ray of frost into a bowl of water (at diner parties and such.)

I'm sure most GMs would allow this, but are there any rules that say that cold damage freezes water into real, useful ice?

Marnath
2010-08-16, 07:10 PM
I don't think it does, the same way most fire spells don't set fires.

elonin
2010-08-16, 07:14 PM
That isn't right. The fire based spells that I'm aware of set fires to unattended objects (including wooden structures). Since the ice spells don't spell that effect out RAW they don't but I'd guess that many dm's would call for that. On the other hand there is a time component with ice creation and if the spell is a instant effect that doesn't last there may not be long enough to freeze the water.

gomipile
2010-08-16, 07:23 PM
Okay, is there a RAW way to reliably create ice at low levels? Wall of Ice would work except that the campaign I want this or will likely never even get to level 6, let alone 8.

AmusingSN
2010-08-16, 07:29 PM
Prestidigitation, a level 0 bard, sorcerer, wizard spell is what you're looking for here.

Rainbownaga
2010-08-16, 07:36 PM
There is a level 6 spell which specifically turns water to ice and deals cold damage Freezing Sphere (http://www.d20srd.org/srd/spells/freezingSphere.htm)

While the very existance of this spell makes it unlikely that cold spells can turn water into ice, there remains the question of how cold damage incapable of freezing water is capable of killing people almost instantly or dealing lethal damage. Remember that air temperatures below freezing only deal non-lethal damage and in real life it takes minutes for someone to die from hypothermia when immersed in extremely cold water.

So no, there is no official rule that I know of, but you can pretty much infer it if you kill enough cat girls.

Roga
2010-08-16, 07:54 PM
A lot of DMs will reward creative thinking. One of my players, years back, was in a town when it got attacked by skeletons. All he had was his +1 Frosty Longsword. Not the best against creatures that take half damage from slashing (3.0 at the time), and no damage from cold. He asked if there was a water source nearby, and there was a quenching barrel in the Forge. He ran over and held his longsword underwater for a round to get a couple inches of ice so he could use it as a bludgeoning weapon.

Not within the rules, but so dang clever I couldn't say no.

Tyndmyr
2010-08-16, 08:58 PM
Prestidigitation, a level 0 bard, sorcerer, wizard spell is what you're looking for here.

This is appropriate. Instant conjurations have the downside of creating ice in your hand, and firing it at the target. As a DM, I'd allow it to create ice cubes in a drink in your hand, but prestidigitation is really the spell for this sort of thing.

Human Paragon 3
2010-08-16, 09:10 PM
I believe somewhere on the SRD, or perhaps in the spell compendium, is a paragraph or two detailing unintended consequences of spells, lighting fires, freezing things, creating fog of war, smoke etc.

Yorrin
2010-08-16, 09:17 PM
Prestidigitation, a level 0 bard, sorcerer, wizard spell is what you're looking for here.

+1 to this. I'm playing a sorcerer right now that does exactly that on a frequent basis.

hamishspence
2010-08-17, 04:39 AM
In D&D, really cold water does nonlethal damage: 1D6 per minute.

I'm not sure but I think there's a general principle that if you fall unconscious from nonlethal damage, subsequent nonlethal damage from the same source counts as lethal.

So, in a few minutes, a 1st level commoner could be killed by cold water:

http://www.d20srd.org/srd/environment.htm


Cold Dangers
Cold and exposure deal nonlethal damage to the victim. This nonlethal damage cannot be recovered until the character gets out of the cold and warms up again. Once a character is rendered unconscious through the accumulation of nonlethal damage, the cold and exposure begins to deal lethal damage at the same rate.



Very deep water is not only generally pitch black, posing a navigational hazard, but worse, it deals water pressure damage of 1d6 points per minute for every 100 feet the character is below the surface. A successful Fortitude save (DC 15, +1 for each previous check) means the diver takes no damage in that minute. Very cold water deals 1d6 points of nonlethal damage from hypothermia per minute of exposure.

Tyrmatt
2010-08-17, 05:04 AM
Is there a Lesser Ice Orb spell, much like the Fire and Acid ones in Spell Compendium? That would actually conjure ice.

I suppose if it's an RP heavy and not needing a huge degree of optimisation (or flaws are allowed) you could take Spell Thematics and use it to generate this kind of effect.

Leon
2010-08-17, 06:12 AM
We had a Dragonborn Paladin kill himself with his Cold breath weapon underwater.

He was sinking fast (as you do when in plate) and decided to make a mini ice berg centered on his arm... it worked all right except for the part with him being under it and torn apart by sharks.

The rest of us recovered his arm, preserved it and mounted it above the fireplace in our base.

Fizban
2010-08-17, 07:10 AM
Frostburn says that 10 points of fire damage will melt 1 cubic foot of ice into "frigid water". I think it would be reasonable to assume that 10 points of cold damage would freeze 1 cubic foot of "frigid water" in turn. Translated into inches, that's 3.8 cubic inches of ice per point of cold damage. If I could find the rules on how much fire damage to boil, I'd go further.

hamishspence
2010-08-17, 07:30 AM
If i'm interpreting this correctly:

http://en.wikipedia.org/wiki/Latent_heat

it requires extra energy to melt ice, than just the temperature change.

Therefore, 10 pts = 1 cubic foot might be quite a conservative estimate for the amount of water you can freeze.

Which means it should be a pretty fair baseline.

Edhelras
2010-08-17, 07:45 AM
The SRD states that:

"Frost
Upon command, a frost weapon is sheathed in icy cold. The cold does not harm the wielder. The effect remains until another command is given. A frost weapon deals an extra 1d6 points of cold damage on a successful hit. Bows, crossbows, and slings so crafted bestow the cold energy upon their ammunition."

So, if a metal object (the weapon) is sheathed in icy cold, and then immersed in cold or neutral water, it would surprise me if icing didn't start to occur on that icy surface. How far that icing would extend, however, I'm not sure. It might, perhaps, depend on the level of the enchantment. Seeing that Ice Storm was one spell that might be used to enchant the weapon thusly, I wouldn't be surprised if the icing effect was strong enough to produce some quantity of ice. The other spell, Chill metal, can also produce freezing temperatures. So I would rule that you could at least break some ice cube sized chunks of ice off that weapon, after it was immersed say for 3 rounds.

Spells targeted on water would be a different question, though. Isn't there a Druid spell that can freeze a body of water, some-cubic-feet-per-level? I believe there is, but couldn't find it on the SRD. Maybe in Frostburn? There should be such a spell, though. Like, if you need to cross a river or lake you can create an ice bridge by freezing the water. But it would probably be higher-level than what you wanted here. Prestidigitation is the best choice for that purpose.

EDIT: As for non-lethal damage by being submerged in icy waters: I don't think there's a general rule that non-lehtal damage is changed into lethal damage when you surpass your current HP? You simply fall unconscious and is helpless. I think what Hamisphence referred to is a property of icy water: That it first deals non-lethal damage, then it deals lethal damage.
If that should be a general property of non-lethal damage, it would be kind of strange to call it non-lethal, you should instead call it slowly accumulative damage or something?
Although I'm a bit puzzled by it all. If you fall unconscious from accumulating non-lethal damage from thirst, what will cause you to die from lack of water? Must be something lethal occurring, at one time or the other.

hamishspence
2010-08-17, 08:01 AM
Heat damage has the same text as cold damage:


Heat Dangers
Heat deals nonlethal damage that cannot be recovered until the character gets cooled off (reaches shade, survives until nightfall, gets doused in water, is targeted by endure elements, and so forth). Once rendered unconscious through the accumulation of nonlethal damage, the character begins to take lethal damage at the same rate.

but I can't find anything in Starvation and Thirst though- it may simply be me assuming too much.

It says it does nonlethal damage:

Starvation And Thirst
Characters might find themselves without food or water and with no means to obtain them. In normal climates, Medium characters need at least a gallon of fluids and about a pound of decent food per day to avoid starvation. (Small characters need half as much.) In very hot climates, characters need two or three times as much water to avoid dehydration.

A character can go without water for 1 day plus a number of hours equal to his Constitution score. After this time, the character must make a Constitution check each hour (DC 10, +1 for each previous check) or take 1d6 points of nonlethal damage.

A character can go without food for 3 days, in growing discomfort. After this time, the character must make a Constitution check each day (DC 10, +1 for each previous check) or take 1d6 points of nonlethal damage.

Characters who have taken nonlethal damage from lack of food or water are fatigued. Nonlethal damage from thirst or starvation cannot be recovered until the character gets food or water, as needed—not even magic that restores hit points heals this damage.

but it doesn't mention taking lethal damage once you're unconscious, unlike Heat & Cold.

Edhelras
2010-08-17, 08:08 AM
Since this is a deviation from the OP topic (Ice cubes at a party), I made a new thread on the topic of non-lethal damage being deadly after all:

http://www.giantitp.com/forums/showthread.php?p=9160905#post9160905

Kylarra
2010-08-17, 08:10 AM
Is there a Lesser Ice Orb spell, much like the Fire and Acid ones in Spell Compendium? That would actually conjure ice.

I suppose if it's an RP heavy and not needing a huge degree of optimisation (or flaws are allowed) you could take Spell Thematics and use it to generate this kind of effect.Technically it creates an orb of acid ... that deals cold damage.

dsmiles
2010-08-17, 08:13 AM
Prestidigitation, a level 0 bard, sorcerer, wizard spell is what you're looking for here.

Prestidigitation is pretty useful. Or look in the 1e Unearthed Arcana. Wizards and sorcerers can invent spells, and 0 level spells should be pretty easy to invent.

Fizban
2010-08-17, 08:35 AM
If i'm interpreting this correctly:

http://en.wikipedia.org/wiki/Latent_heat

it requires extra energy to melt ice, than just the temperature change.

Therefore, 10 pts = 1 cubic foot might be quite a conservative estimate for the amount of water you can freeze.

Which means it should be a pretty fair baseline.

You'd think I'd remember that, I love pointing that out about steam burns.

Blaugh, it's summer and I don't like chemistry conversions anyway. But It someone runs the numbers, we could get how much energy those 10 points of fire damage represents, and convert that into temperature change for water. The amount of energy required to change 1 cu ft of water from solid to liquid= 10 points of fire damage. Then run that amount of energy through the specific heat and figure out how much it heats up. And have fun converting between the different units in each section of wikipedia.

ericgrau
2010-08-17, 09:59 AM
In the case of freezing sphere magical ice is formed, which disappears after a short duration. Fireball doesn't start fires because it is too brief. Cone of cold is likewise brief, so how much ice it can make I cannot say. I can say that it takes a ton of cold to freeze water, and an instantaneous spell may have a difficult time doing it even with high damage. So for game, practical and realistic purposes I'd say no, the water doesn't freeze except for a very thin layer. If we can make some assumptions about the energy contained in a fire/cold spell, I could estimate how much but I doubt it is much.


If i'm interpreting this correctly:

http://en.wikipedia.org/wiki/Latent_heat

it requires extra energy to melt ice, than just the temperature change.

Therefore, 10 pts = 1 cubic foot might be quite a conservative estimate for the amount of water you can freeze.

Which means it should be a pretty fair baseline.
It also takes extra cold to freeze ice, exactly the same amount in fact. 10 pts for a cubic foot doesn't sound too bad. I mean that's 250 damage for a 5x5 square to 1 foot deep. Or 4" deep for a CL 15 cone of cold. If anything I'd say it takes more damage, but whatever, might as well use their number.

hamishspence
2010-08-17, 10:03 AM
In the case of freezing sphere magical ice is created, which expires after a set duration. Fireball doesn't start fires because it is too brief. Cone of cold is likewise brief, so how much ice it can make I cannot say. I can say that it takes a ton of cold to chill ice, and an instantaneous spell may have a difficult time doing it even with high damage. So for game, practical and realistic purposes I'd say no, the water doesn't freeze except for a very thin layer. If we can make some assumptions about the energy contained in a fire/cold spell, I could estimate how much but I doubt it is much.

This bit here:


Frostburn says that 10 points of fire damage will melt 1 cubic foot of ice into "frigid water". I think it would be reasonable to assume that 10 points of cold damage would freeze 1 cubic foot of "frigid water" in turn. Translated into inches, that's 3.8 cubic inches of ice per point of cold damage. If I could find the rules on how much fire damage to boil, I'd go further.

gives us a rough idea of how much energy is released when 10 points of fire damage are done.



It also takes extra cold to freeze ice, exactly the same amount in fact .

Freezing releases energy- it doesn't consume extra energy- it's exothermic:

http://en.wikipedia.org/wiki/Freezing

but it does require an ambient temperature slightly below the freezing point.

Twilight Jack
2010-08-17, 10:17 AM
Well, a cubic foot of water weighs a little over 62 lbs., or 28 kg. Let's work metric, since that's a little cleaner.

The heat of fusion for ice is equal to 333.55 joules/g. That converts to 333,550 joules/kg. So it takes 9,339,400 joules to melt 1 cubic foot of ice into frigid water. Which allows one to infer that a single point of fire damage puts out 933,940 joules, or 885.2 BTU.

Make of that what you will.

jseah
2010-08-17, 10:26 AM
Used Google to do the conversions:
heat of fusion of ice = 333.55 kJ/kg
density of ice = 0.9167 g/cm³ at 0°C

1 cubic foot of ice = 28 316.8466 cubic centimeters = 25958.0532 g = 25.9581 kg

By that measure, 10 points of fire damage =
8658.3087 kJ
8.6583 MJ
megajoules. =)


Another one to try is melting wall of Ice.
-> Link to my old calculations when I find it.
EDIT:
Calculated using wall of ice
http://www.giantitp.com/forums/showpost.php?p=7499319&postcount=29

Calculated using wall of water
http://www.giantitp.com/forums/showpost.php?p=7500548&postcount=37

Note the massive difference

hamishspence
2010-08-17, 10:33 AM
Sandstorm has the temperature levels for the ambient air temperature to do fire damage.

They aren't really all that high. Using 1 cubic ft of ice, a temperature high enough to do 1d6 fire damage per round would, on average, melt it in 3 rounds. Yet only be something like 160 Fahrenheit or so (maybe a bit higher?)

I wonder- how thin would a sheet of ice need to be, for air that temperature to melt it in 18 seconds?

Twilight Jack
2010-08-17, 10:43 AM
jseah's calculations are a bit more exact than mine, as I started from the weight by volume of water, rather than ice. Since water expands as it freezes, the cubic foot of ice weighs less, but no longer takes up a whole cubic foot once melted.

jseah
2010-08-17, 10:48 AM
Oh, also, another old calculation. This time using burning oil and trying to equate it with wall of fire.

I used the higher heating value of kerosene to simulate oil.

http://www.giantitp.com/forums/showpost.php?p=7507937&postcount=81

EDIT:
I might like to point out an interesting observation.

Among the four ways I have calculated the power output of fire damage, all the values are in the megajoule range. There's about 1 order of magnitude difference between the results but that shows at least some consistency.

hamishspence
2010-08-17, 10:51 AM
Ordinary air, at (I think) 451 F in Sandstorm, could be a mundane source that does 3d10 fire damage (on average between 16 and 17 points) per round.

Any calculations that can be drawn from that?

ericgrau
2010-08-17, 11:23 AM
Not easy ones. Natural air convection due to temperature difference and the resulting heat transfer is astoundingly complicated.

And as long as you're using a random book as the source, the amount of energy removed to freeze water is exactly the same as the amount added to melt it. So that would make the answer 10 damage per cubic foot.

gomipile
2010-08-17, 02:02 PM
This bit here:



gives us a rough idea of how much energy is released when 10 points of fire damage are done.



Freezing releases energy- it doesn't consume extra energy- it's exothermic:

http://en.wikipedia.org/wiki/Freezing

but it does require an ambient temperature slightly below the freezing point.

Yes, you are right, but work is still required to pump that energy out of the ice. From the perspective of the water freezing into ice, it is an exothermic process, but that process is only part of the entire system. The heat released by the ice has to be pumped away in order for the ice to freeze. You need to create and maintain an environment around the ice at a low enough temperature that ice can remain frozen while in thermal equilibrium with that environment. The pumping away of the heat released by the ice is what requires work. In the case of an ordinary freezer, the work is done in the compressor.

This is why both heaters and freezers require power from your wall outlet.

Erom
2010-08-17, 02:06 PM
Note it isn't uniform either - I'd imagine for most spells, if you accept the 10dmg = 1 foot thing, and you dealt 100 cold damage, you wouldn't get 10 feet of ice at freezing. You would get a smaller volume with some of it cooled even colder than freezing. I imagine the temperature gradient would vary by what spell you used or something.

TLDR version: Fluids are difficult and especially catgirl-y.

gomipile
2010-08-17, 02:09 PM
TLDR version: Fluids are difficult and especially catgirl-y.

Yep, million-dollar prize difficult: http://www.claymath.org/millennium/Navier-Stokes_Equations/.

LibraryOgre
2010-08-18, 12:25 AM
We had a Dragonborn Paladin kill himself with his Cold breath weapon underwater.

He was sinking fast (as you do when in plate) and decided to make a mini ice berg centered on his arm... it worked all right except for the part with him being under it and torn apart by sharks.

The rest of us recovered his arm, preserved it and mounted it above the fireplace in our base.

Ok, that's hilarious.

Ad res, I'd allow someone to use Ray of Frost to create a little bit of ice. I wouldn't let a PF sorcerer freeze an entire pond, but a little bit works just fine.

Ormur
2010-08-18, 03:21 AM
To put megajoules into perspective I checked Wikipedia and it said that it was the equivalent of the kinetic energy of a one ton vehicle moving at 160 km/h and the heat given of a human at rest over a bit less than three hours.

So one point of fire damage is a little less than that.

Kobold-Bard
2010-08-18, 04:04 AM
Haven't read the full thread (science scares me) but prestidigitation is what you need, specifically the Chill option from here http://www.wizards.com/default.asp?x=dnd/ex/20010707

hamishspence
2010-08-18, 04:07 AM
Haven't read the full thread (science scares me) but prestidigitation is what you need, specifically the Chill option from here http://www.wizards.com/default.asp?x=dnd/ex/20010707

It won't produce any ice- which is what the OP wanted- but it will make the drink cold.

Was Snilloc's Snowball a Conjuration spell or an Evocation spell? I think it was in FRCS, and was a really low powered cold spell that produced a snowball that did low Cold damage.

Kobold-Bard
2010-08-18, 04:23 AM
It won't produce any ice- which is what the OP wanted- but it will make the drink cold.

Was Snilloc's Snowball a Conjuration spell or an Evocation spell? I think it was in FRCS, and was a really low powered cold spell that produced a snowball that did low Cold damage.

True, but for 900gp you fan make a pendant that will let you cast it at-will which I'd consider better.

Lesser Orb of Ice maybe?

Peregrine
2010-08-18, 06:44 AM
It won't produce any ice- which is what the OP wanted- but it will make the drink cold.

Why not? It says it won't reduce the temperature below freezing, but it will therefore reduce it to freezing. :smallbiggrin:

hamishspence
2010-08-18, 07:18 AM
But, water doesn't actually freeze at "freezing" (32 F) but at a degree or so below- due to the extra energy needed to force a phase transition.

Peregrine
2010-08-18, 08:19 AM
But, water doesn't actually freeze at "freezing" (32 F) but at a degree or so below- due to the extra energy needed to force a phase transition.

Nope. :smallsmile: 0.01°C, or just ever so slightly above freezing, is the triple point of water: the temperature at which ice, liquid water and water vapour can all coexist without changing phase.

You're right about the energy, but the thing is, this energy doesn't change the temperature -- it's latent heat. So if you can sustain a temperature that's dead on freezing, you will get ice. Physics tells us you need to keep transferring energy, but prestidigitation merely says it can cool to a specific temperature, regardless of the thermodynamics involved. QED. :smalltongue:

hamishspence
2010-08-18, 08:24 AM
Unless it's salt water- which freezes at a temperature slightly below 32F.

Depending on the air pressure, even cooling water to exactly 32F will not freeze it.

Conversely, at low air pressures, it will freeze at higher temperatures:

http://en.wikipedia.org/wiki/Ice

If you apply prestidigitation to a liquid that's not pure water, its temperature will not drop below 32F.

Lysander
2010-08-18, 08:35 AM
I agree with the whole creative thinking thing. However I'm not sure most cold spells produce real ice. Even Freezing Sphere which specifically says it freezes water doesn't really produce real non-magical ice:


If the freezing sphere strikes a body of water or a liquid that is principally water (not including water-based creatures), it freezes the liquid to a depth of 6 inches over an area equal to 100 square feet (a 10-foot square) per caster level (maximum 1,500 square feet). This ice lasts for 1 round per caster level. Creatures that were swimming on the surface of frozen water become trapped in the ice. Attempting to break free is a full-round action. A trapped creature must make a DC 25 Strength check or a DC 25 Escape Artist check to do so.

The existence of the ice is part of the spell's duration.

hamishspence
2010-08-18, 08:38 AM
Could be that the spell instantaneously (artificially) causes a drop in temperature in a very specific area of water, which promptly becomes ice.

The moment the duration ends, the temperature, throughout the ice, returns to normal- and the ice instantaneously melts.

Erom
2010-08-18, 08:51 AM
If you apply prestidigitation to a liquid that's not pure water, its temperature will not drop below 32F.

And nearly everything you can actually drink is not pure water. You don't even want it to be pure water. The lab techs always used to quip that water once it hit triple-distilled purity could pull fillings off of your teeth.

hamishspence
2010-08-18, 08:56 AM
I was thinking of liquids like juice, or oil, or some other things- you can reduce them to 32F, but, unless their freezing point is above that, you can't freeze them.

Hmm- do the impurities in "typical rainwater" make it freeze above 32F, or not?

ericgrau
2010-08-18, 10:45 AM
You can't freeze water without bringing the temperature below freezing because if the water is at 32 and the surrounding area is at 32 then heat transfer is zippo so you can't remove any heat away from the water to freeze it. Or if the temperature difference is 0.01 degrees, then heat transfer is so low it might as well be zippo.

Peregrine
2010-08-19, 08:29 AM
Unless it's salt water- which freezes at a temperature slightly below 32F.

Depending on the air pressure, even cooling water to exactly 32F will not freeze it.

Conversely, at low air pressures, it will freeze at higher temperatures:

http://en.wikipedia.org/wiki/Ice

If you apply prestidigitation to a liquid that's not pure water, its temperature will not drop below 32F.

Ah, but will it? Does prestidigitation reduce the temperature to "freezing" or to "32°F"? The linked page says both. :smalltongue:

(Yeah, I know, that one was pretty thin. 32°F/0°C is called "freezing" even when there's nothing to actually freeze.)


You can't freeze water without bringing the temperature below freezing because if the water is at 32 and the surrounding area is at 32 then heat transfer is zippo so you can't remove any heat away from the water to freeze it. Or if the temperature difference is 0.01 degrees, then heat transfer is so low it might as well be zippo.

Heat transfer is not environmental in this situation -- it's magical. You can use prestidigitation to cool something to 32°F even when the air temperature is over 70°F.

Actually, depending on how you read it, you can cool the object from 72°F, and have it remain at 32°F for an hour, even if you then take it into 100°F air. Or drop your magic ice cubes into room-temperature drinks. Continuously cold drinks for an hour!