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An interesting "solution" to dealing with environments of extreme heat would potentially be to utilize things similar to brown mold or other dungeon hazards that alter the environment around them.
Has anyone worked out the fantasy physics of the interaction between brown mold and lava?
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It's called "Irrisen."
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An interesting "solution" to dealing with environments of extreme heat would potentially be to utilize things similar to brown mold or other dungeon hazards that alter the environment around them.
Has anyone worked out the fantasy physics of the interaction between brown mold and lava?
Everything has limits. That's why one patch of brown mold has not absorbed all of the heat that exists in the universe. I'd rule that molten lava would easily exceed the limits of brown mold to absorb heat and it would become crispy critterfied.
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^ Fantastic visuals.
However, the hardened rock may or may not sink depending on the viscosity of the molten rock as compared to the mass and displacement of the rock hardened by the brown mold.
Similar scenario:
What about having brown mold simply sitting on the edge of the lava pool? Would the brown mold growing cause the hardened lava below it to grow as well?
I like the idea of the cold damage directly lowering the environmental damage of the lava.
Due to nonlethal damage needing to surpass a creatures hit points twice in order to kill, Nonlethal damage can be described as being roughly 1/2 lethal damage.
So, extreme heat does 1d6 damage per 10 rounds (1 minute) -- or 2d6 per minute of nonlethal equivalent damage, whereas brown mold does 30d6 nonlethal per 10 rounds (1 minute), or 15d6 of equivalent lethal damage. Brown mold is "colder" than lava is "hot". By about 15x.
Would the change in air temperature push hot air into the brown mold's "air space" via convection? (Would this make physics happy)? Convection can also carrying open flame along with it, as fire follows wind.
This would cause the brown mold to spread at it's normal progression until the lava is essentially crusted over enough to no longer feel the heat from the lava through the hardened stone.
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Ok, so beyond the initial spread, there wouldn't be any further spread due to the cold radius keeping the heat from the lava away from the brown mold.
It would be required to be "helped along" in order to fully harden any flow larger than the patch.
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It was controlled in 3e by the fact molds and fungi were extremely sensitive to ultraviolet light. Being outside killed off most kinds of magical fungi and molds very quickly, which is why they were only found in subterranean places.
You'll notice they stick to the same tropes. Brown mold isn't found outside in any source I can think of, and most magical fungi is found underground as well (exceptions for some that are faerie affiliated).
Same thing goes for oozes and puddings, by, the way. that's why endless numbers of black puddings haven't consumed everything organic on the planet.
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For the sake of playability*, I'd like to present an alternate interpretation of the encounter with a pool of lava. Assuming a pool large enough and deep enough that we need only consider the mold's effects, and taking the ruling in Avoron's post where the mold makes an island...
The island begins to sink. Lava laps around the edges, enters the field of the mold, and is chilled to solidity, forming a lip of stone at the edge of the island. If not yet a buoyant unit, the island sinks further, the lip chills again, and again, until the island is a boat. The traditional bubbling of the lava wobbles things a bit, the lip builds a bit more, and we can either take on cargo/ballast/crew (slowly) or chuck it out to adjust our waterline.
Aside from propulsion, we're set to sail the Lava Sea. With more islands, we might build a catamaran. Perhaps powered by a heat exchange engine.
*Not in the 'every party should have three of these' sense, but in the 'SOME party should do this at least once', sense.
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For the sake of playability*, I'd like to present an alternate interpretation of the encounter with a pool of lava. Assuming a pool large enough and deep enough that we need only consider the mold's effects, and taking the ruling in Avoron's post where the mold makes an island...
The island begins to sink. Lava laps around the edges, enters the field of the mold, and is chilled to solidity, forming a lip of stone at the edge of the island. If not yet a buoyant unit, the island sinks further, the lip chills again, and again, until the island is a boat. The traditional bubbling of the lava wobbles things a bit, the lip builds a bit more, and we can either take on cargo/ballast/crew (slowly) or chuck it out to adjust our waterline.
Aside from propulsion, we're set to sail the Lava Sea. With more islands, we might build a catamaran. Perhaps powered by a heat exchange engine.
*Not in the 'every party should have three of these' sense, but in the 'SOME party should do this at least once', sense.
See, that's the thing. The viscosity of the lava coupled with the bowl like shape of the hardened lava, I believe, would create a displacement of the lava that would ensure buoyancy. You could make it even more buoyant by using stone shape to make it more triangular.
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For the sake of playability*, I'd like to present an alternate interpretation of the encounter with a pool of lava. Assuming a pool large enough and deep enough that we need only consider the mold's effects, and taking the ruling in Avoron's post where the mold makes an island...
The island begins to sink. Lava laps around the edges, enters the field of the mold, and is chilled to solidity, forming a lip of stone at the edge of the island. If not yet a buoyant unit, the island sinks further, the lip chills again, and again, until the island is a boat. The traditional bubbling of the lava wobbles things a bit, the lip builds a bit more, and we can either take on cargo/ballast/crew (slowly) or chuck it out to adjust our waterline.
Aside from propulsion, we're set to sail the Lava Sea. With more islands, we might build a catamaran. Perhaps powered by a heat exchange engine.
*Not in the 'every party should have three of these' sense, but in the 'SOME party should do this at least once', sense.
See, that's the thing. The viscosity of the lava coupled with the bowl like shape of the hardened lava, I believe, would create a displacement of the lava that would ensure buoyancy. You could make it even more buoyant by using stone shape to make it more triangular.
And thus, the city that floats through the Burning Lands was formed. Where centuries before, careless magicians tore open rifts to the Earth and Fire Planes in an attempt at infinite power.
As we are handwaving away physics here almost completely, I'm not really sure we should make any predictions.
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There is also the fact that if the mold cooled enough of the lava to plug the volcano completely, your going to eventually have a massive eruption on the scale of Krakatoa that would likely destroy half the mountain, kill everything within a 300 mile radius, and cause tsunamis and a few years without a summer.
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As we are handwaving away physics here almost completely, I'm not really sure we should make any predictions.We're not handwaving away all physics, just the parts that say magic can't keep things cold.
Actually, yes you are. If you assume you are maintaining a 30' ball of 10-40F temperature you have issues of boundary layer conduction and blackbody radiative heat transfer to consider. If the brown mold can maintain that temperature no matter what, it has to be either an infinite heat sink, or somehow there is a perfect adiabatic layer at that radius (which would prevent all radiation, including light from moving back and forth).
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As far as I can understand it, brown mold uses up heat. It doesn't have to be able to absorb an infinite amount, only enough heat per round. Perhaps it converts the energy into matter to reproduce.
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I think the mold would incinerate, but here are a few thoughts if not or even if:
Case 1, the boat:
Hmmmmm....I do not think it would form a traditional boat, as the lava lip formed would be hemispherical. Somewhere near the top of the sphere, there's be a hole as it bobbed along.
Case 2, the lava burns the mold when it expands toward the lava, but that burning fuels expansion above the burn:
I say this breaks down into "burns organic matter" levels of heat which we will call "fire" and "So hot it even burns the mold" levels of heat which we will call "plasma". Basically molten rock is MUCH hotter than molten halfling.
At some point in it's decent into the giant lava pit, the mold is going to cross the radiation boundary at which point "fire" happens to the edge of the mold and it doubles in size, fueled by it's own burning. This point is past the basic "fire" point, because the mold chills around it and there will be a soaking of energy as the mold travels through the "fire" gradient into the "plasma" gradient.
If the mold expands in all directions and anything that expands down burns again, you would effectively cap the fire/plasma with the mold, as it feeds itself on it's own fire.
It get's weirder. Convection currents would churn up the cap, forcing it to break up, float up and then back down, filling the chamber above the lava. This cycle would continue until the chamber was full of mold above the plasma line.
Sadly, the currents would start to build up pressure. Pressure is heat effectively, so the dense mass of mold would begin raise in temperature, even as it chilled. Eventually, this would raise the effective "plasma" layer's height, eventually burning out all of the mold in many cycles.
But...if there was even a single passage out of the cavern, this would give a pressure valve and the mold would march out of the cavern wave after wave.
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I miss the days where naive players believed a fistful of brown mold thrown through a portal would wipe out all of hell.
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There is also the fact that if the mold cooled enough of the lava to plug the volcano completely, your going to eventually have a massive eruption on the scale of Krakatoa that would likely destroy half the mountain, kill everything within a 300 mile radius, and cause tsunamis and a few years without a summer.
Well, that kind of depends on whether there are other outlets for the resulting pressure. If there are enough out-fissures in the volcano's base, you'd just have a greater outpouring of magma through those channels.
Actually, yes you are. If you assume you are maintaining a 30' ball of 10-40F temperature you have issues of boundary layer conduction and blackbody radiative heat transfer to consider. If the brown mold can maintain that temperature no matter what, it has to be either an infinite heat sink, or somehow there is a perfect adiabatic layer at that radius (which would prevent all radiation, including light from moving back and forth).
Well, in my original idea we would have convective heat exchange between the air above the lava and the air around the mold, but I was dissuaded of that idea.
Remember, that according to the equation of lethal to non-lethal damage, brown mold is something like 15x more powerful in it's heat sink effect than lava is in generating heat.
I'm not ultimately familiar with physics, but how would the heat sink prevent light from reflecting off the mold? Unless you think the photon particle would be cooled and no longer be visible because of it. (Is this it?) --
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Sideromancer: Ah, I see (after doing some googling).
bulbaquil: Actually, the brown mold entry does say it "Brown mold feeds on warmth, drawing heat from anything around it."
So, there is a transfer of energy between the area outside the 30' lowered temperature radius and the surrounding room.
I'm re-thinking my thermal convection idea. If we follow standard (very "soft described") thermal models for air, the brown mold would create a low pressure area where the temperature is less than the surrounding lava pool, and the high pressure hot air created by the lava would pool in, cool down, and then move out as a result of differences of air pressure.
This would still not allow for the brown mold to spread itself, as there would be no open flame that would allow for it, but it would increase the area of solidified lava to something just a little bit bigger than the 30' radius of the temperature reduction.
The mold would still be able to maintain the 30' radius of 40 degree temperature, but there would still definitely be air movement and corresponding heat into the area of cold.
There is the question as to just how much lava heated air is enough to overwhelm the brown mold.
With a 15-1 ratio, one 5' patch of brown mold should be able to maintain itself against fifteen 5' squares of lava. Once you get to something larger lava-wise, the brown mold's temperature reduction would start to lessen, and you'd need more patches of brown mold to keep the pace.
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In a volcano, you'd have a literal tempest.
Because the amount of heat transfer is unlimited and instantaneous, you'd have a massive current of hot air hitting the radius, cooling down and increasing in weight, causing more hot air to fill in and follow the cold air, which would be pushed out to the sides, instantly reheat and be pushed back into the air.
In short order, you'd have a tornado forming, which would likely rip the mold to shreds and stop the effect entirely, no?
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Wouldn't that split the now bigger patch into two, then those patches would grow individually, and if they are being tossed about by wind, they'd start growing..yes?
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Minor differences in temperature, less then 20 degrees, are what drive tornadoes to form. Remember, Pressure = Volume x Temperature.
You have a difference of hundreds, if not THOUSANDS, here. The convection currents that would be set up would escalate very quickly. Superheated air hitting extremely cold air sets up convection currents VERY quickly, as the warm air tries to move past the heavy, cold air, and the whole mass starts to spinning very quickly. The pressure differentials of air going suddenly from one extreme to the other would generate a LOT of turbulence, and just start shredding the mold until there's not enough left to hold the cooling effect, and it would just collapse.
That's in the real world, tho.
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The cold air within the radius has absolutely no reason to exit the sphere into the higher-temperature surroundings.
The increased density of the cold air causes it to "fall", which is then replaced by the lesser dense hot air surrounding the sphere. The hot air around the sphere naturally rises, creating a vacuum effect that the colder air shifts into. Coriolis effect causes rotation.
Natural convection. Cold air out at the "floor" and hot air in from the ceiling.
I'm not convinced that you'd have tornado strength winds, though, considering the relatively small size of the volume of cold air, though.
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I was thinking about submitting it to Because Science on Nerdist.com
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First of all, we're talking about a mold that is dropped onto lava. There is nowhere beneath it for cold air to fall through. Secondly, even if the mold was somehow floating in midair, I'm not sure the cold air would actually have time to fall out of the sphere for a significant distance before being reheated by the hot air beneath, or at the very least being replaced by the heated and pressurized air directly below it just waiting to rise. You'd get a fuzzier, less precise bottom edge to the sphere, but I definitely don't think you'd encounter any major vacuum forces.
Oh, agreed that you wouldn't have a level of wind speed equalling a tornado or anything like it. But the 30' radius wold give you a 30 foot hemisphere if it were dropped in initially. The air from the top of the hemisphere would push out the air at the sides into the area around the hemisphere which would draw in the hotter outside air. So, you'd have convection, but not any sort of true vacuum.
At least, imo.
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I've seen people make up a fire tornado/whirlwind just from burning buckets of gasoline.
You have a convection cycle here nearly an order of magnitude bigger.
Hot air outside the mold is moving skywards. That's a thermal. The thermal from a volcano is VERY strong. Grab a parachute, it'll launch you WAY up into the sky.
That 2000+ degree hot air hits the area of the mold and instantly cools down. THe effect is the exact same thing as if you blow up a ballon with hot air and throw it in the freezer...it's going to shrink in size tremendously.
This creates a vacuum effect on the surrounding air as the cold air collapses into a denser, cooler mass. The heavy air falls to the ground, spreads out in a 'pool' of heavier air as more air falls from above, driving out around it equally...into the very light, superheated air outside.
That cold air is going to act like a blanket, weighing down the hot air even as the hot air heats it up. The fast-rising hot air will push it aside, but the cold air still has to go SOMEWHERE as it is reheated, so it gets pushed to the side even as endless amounts more of it are being pushed out.
The cold air is moving sideways now, alternately being shoved to the side, and lifting itself as it gets warmer on a bed of fast-moving hotair, which it is still heavier then and so the hot air is also moving sideways as it goes around it.
Bingo, you have a vortex forming, a whirlwind. As the air spins, it grabs onto the air around it, inciting that into motion, as layers of hot and cold air begin to cycle and spin and move upwards, driven by the hot airs desire to rise and the cold air's desire to sink moving past one another.
In the center of the vortex, you still have a vaccuum as the light, hot air outside is being drawn in, turned into much denser, heavier cold air, and pushed out to the sides, forcing the vortex outside away from the cold center. However, friction is still grabbing the air, and so all the air is going to be spinning by now, building in velocity as the massive temperature differentials and air pressure differences drive the whole thing forwards like some perfect engine.
The resulting winds will rip apart the mold, break the temperature differential, scatter the mold, and return the volcano to its normal thermal cycle as the engine of change disappears.
This creates a vacuum effect on the surrounding air as the cold air collapses into a denser, cooler mass.You still seem to be describing a situation where the brown mold just pops into existence in the middle of the volcano, instantly cooling the air around it and creating a massive difference in pressure. But that's not the case. As the mold approaches and enters the volcano, more and more air will seep into the radius. By the time it gets anywhere near the actual lava, the pressure inside and outside of the circle are exactly the same, because that's what pressure does. The air inside the circle is just denser. As the mold moves, additional air will enter, but only enough to compensate for the air that moves out - the extreme forces your talking about just don't have sufficient reason to come into play, especially if the mold is sitting on lava and does not have any space below it for air to fall into.
I have no idea what you are talking about.
I'm describing a patch of brown mold sitting on a rock in the middle of a volcano. Hot and cold air would spin around the boundary of the mold's effect, while hot air gets sucked in from above, and the vortex whips the surrounding air into a whirlwind of motion.
What are you describing? Brown mold floating in midair? I'm lost.
No, a convective cell will be set up at the boundary of the 30' radius sphere. You have a strong temperature gradient in the air, it will drive movement.
A 1000-2000 degree temperature differential might indeed be described as 'strong'. Tornadoes form off of 10-20 degree differentials!
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No, a convective cell will be set up at the boundary of the 30' radius sphere. You have a strong temperature gradient in the air, it will drive movement.A 1000-2000 degree temperature differential might indeed be described as 'strong'. Tornadoes form off of 10-20 degree differentials!
We'd have essentially would be the eye of a hurricane type effect.
And while I believe you about tornadoes forming off of 10-20 degree differentials, the volume of air with that differential is much much greater.
We'd have a vortex, true. But I don't think you'd be able to get that level of wind speed off of a sphere of air 30' in radius.
I'd love to be proven wrong though, the visuals on this are awesome.
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The air coming up off a volcano is MOVING. It's not sitting there...it's a very strong thermal updraft.
You're trying to throw a wet blanket on top of it of cold air. The two streams are going to slide around one another as they get lifted up in the air, and form a convection current. In the middle of them, more air is going to be falling down/getting sucked into the dome of cold...that stream of air coming down is going to be even stronger then the one going up because of the pressure differentials, and the compression of the hot air.
Gonna have to ask some aerodynamic guys to model this to get a real answer!
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The air coming up off a volcano is MOVING. It's not sitting there...it's a very strong thermal updraft.
You're trying to throw a wet blanket on top of it of cold air. The two streams are going to slide around one another as they get lifted up in the air, and form a convection current. In the middle of them, more air is going to be falling down/getting sucked into the dome of cold...that stream of air coming down is going to be even stronger then the one going up because of the pressure differentials, and the compression of the hot air.
Gonna have to ask some aerodynamic guys to model this to get a real answer!
Agreed that we have that kind of effect. I just saw a youtube video with some kids, hot water and dry ice in a box with a fan (search for tornado science experiment) creating low pressure in the box itself. While the box was closed, the slits in the sides of the box allowed for a vortex to form when the fan was on -- the slits allowed for a sheering winds. But when a square was removed from the back of the box, the sheering effect was lost (with the same fan creating a low pressure effect in the system).
I'm not seeing where there would be the sheering effect necessary for a vortex to form.