The current arc in my game brought my players to an underwater kingdom to overthrow a corrupt sea elf king (one of the PC's is the rightful ruler and his half sister). The combat was ridiculous and a lot of it surrounded the physics of lightning underwater. I have done some research since on the physics of lightning and water and would like some input.
Because water isn't necessarily a great conductor of electricity, I want to leave the AOE and damage as is, but I was reading that when lightning strikes the surface it creates a huge sound wave. I was thinking anyone within a certain range (maybe 100 ft?) makes a con saving throw or takes 3d10 force damage and becomes deafened and takes half damage on a success and does not become deafened.
another idea that I use is, because sea water is way more conductive than air, you could double the width of the attack, but half the range.
for example chain lighting would have half the range but effect double the number of targets. chaos bold and chromatic orb would have half the range but act as a beam, dealing less damage to creatures in the beam, and full damage at the end of the beam. lightning bolt would extend 50 feet instead of 100, but the beam would be 10 feet across.
i like this because it maintains the idea of magic directing the lightning to its target (instead of just arcing to the nearest grounding point) but it still lets water effect the lightning, and allows the player to do some cool stuff if they're creative enough
D&D magic lightning is magic. It doesn't need to work like real lightning.
In reality,
Water is quite conductive it's why there are electric devices for stunning fish that researchers use to survey aquatic habitats. Note that fleshy bodies are usually similarly conductive to water or less conductive than water, this means electricity in water disperses very easily rather than concentrating into an arc like it does when it travels through air as lightning. This would mean spells like Lightning Bolt would function as an Emanation around the caster and be far shorter range and deal far less damage to each individual target -> e.g. a 30 ft emanation that deals 2d6 damage rather than a 100 ft line that deals 8d6 damage.
Lightning striking water only has striking effects because the lightning travels through air before hitting the water. That travel through air forces the lightning to be super concentrated because air is extremely non-conductive. That super concentrated lightning becomes extremely hot and turns the air into plasma causing it to light up and be the visual lightning we can see. If you apply current to water that electricity is always invisible because it disperses through the conductive medium (water) long before heating up enough to create plasma. When lightning strikes water the explosive effect occurs because of the super-heated plasma at the surface of the water instantly boils the water creating gaseous water vapour faster than the vapour can disperse thus generating high-pressure gas that when it reaches the critical pressure explodes causing a loud noise and big wave across the surface of the water. However, only a few feet below the surface that lightning strike has very little effect because the heat doesn't penetrate and the electricity disperses to the cube of the distance from the strike point. This is why you don't see masses of dead fish after lightning hitting a lake or river.
So if magical lightning works like real lightning in your game, it would be largely ineffectual when used underwater.
Just use the spell as-is. I’ll point out a line from the ‘24 DMG:
Rules Aren’t Physics. The rules of the game are meant to provide a fun game experience, not to describe the laws of physics in the worlds of D&D, let alone the real world.
Do you really want to start measuring the effects of lightning in fresh water vs salt water? What about thunder damage, as sounds travels differently through water than it does air? Does the poison from poison spray just dissipate harmlessly in the water? It just opens a real can of worms that, imo, doesn’t actually make the game more fun.
I think that ultimately depends on the group, and I was coming up with a base to use for this particular table as they like to discuss physics. Having a plan out the gate for the future will just save a lot of side conversations that distract not only me, but the other players as well.
It kind of is. At this point I've told them they can send me what it is they would like to use and I will get them underwater mechanics for those things or they can use them as written.
Thunder damage is, I think, the only one that realistically would deal more damage underwater than in air. Though for sound it's pretty unclear since different frequencies travel differently in water vs air, but I always imaging thunder damage as a thudding base noise which would travel well in water. Fire is already halved RAW, lightning would become emanations with the damage cube-rooted, force is unaffected, radiant would be slightly reduced since most water blocks light more than air does, necrotic would be unaffected,..
Cold... hm.. cold is an interesting case. Water's extremely high heat capacity that causes fire damage to be halved should really also halve cold damage. Though if the cold is so cold as to freeze the water then it should impose movement penalties on its wet victims.
Acid should be completely ineffective since it would instantly dilute and get buffered by the bicarbonate dissolved in water.
Aquatic creatures should maybe have vulnerability to poison since the (relatively) low amount of oxygen dissolved in water means most of them have greater permeable membranes to absorb dissolves gases / nutrients in the water. Certainly amphibians are very sensitive to toxins in their water. Not sure about this one though, air-breathing creatures also need lots of permeable membranes to absorb oxygen effectively into their water-filled bodies.
Hi all!
The current arc in my game brought my players to an underwater kingdom to overthrow a corrupt sea elf king (one of the PC's is the rightful ruler and his half sister). The combat was ridiculous and a lot of it surrounded the physics of lightning underwater. I have done some research since on the physics of lightning and water and would like some input.
Because water isn't necessarily a great conductor of electricity, I want to leave the AOE and damage as is, but I was reading that when lightning strikes the surface it creates a huge sound wave. I was thinking anyone within a certain range (maybe 100 ft?) makes a con saving throw or takes 3d10 force damage and becomes deafened and takes half damage on a success and does not become deafened.
Thank you in advance!
another idea that I use is, because sea water is way more conductive than air, you could double the width of the attack, but half the range.
for example chain lighting would have half the range but effect double the number of targets. chaos bold and chromatic orb would have half the range but act as a beam, dealing less damage to creatures in the beam, and full damage at the end of the beam. lightning bolt would extend 50 feet instead of 100, but the beam would be 10 feet across.
i like this because it maintains the idea of magic directing the lightning to its target (instead of just arcing to the nearest grounding point) but it still lets water effect the lightning, and allows the player to do some cool stuff if they're creative enough
I definitely wouldn't have thought of that! Thank you!
D&D magic lightning is magic. It doesn't need to work like real lightning.
In reality,
Water is quite conductive it's why there are electric devices for stunning fish that researchers use to survey aquatic habitats. Note that fleshy bodies are usually similarly conductive to water or less conductive than water, this means electricity in water disperses very easily rather than concentrating into an arc like it does when it travels through air as lightning. This would mean spells like Lightning Bolt would function as an Emanation around the caster and be far shorter range and deal far less damage to each individual target -> e.g. a 30 ft emanation that deals 2d6 damage rather than a 100 ft line that deals 8d6 damage.
Lightning striking water only has striking effects because the lightning travels through air before hitting the water. That travel through air forces the lightning to be super concentrated because air is extremely non-conductive. That super concentrated lightning becomes extremely hot and turns the air into plasma causing it to light up and be the visual lightning we can see. If you apply current to water that electricity is always invisible because it disperses through the conductive medium (water) long before heating up enough to create plasma. When lightning strikes water the explosive effect occurs because of the super-heated plasma at the surface of the water instantly boils the water creating gaseous water vapour faster than the vapour can disperse thus generating high-pressure gas that when it reaches the critical pressure explodes causing a loud noise and big wave across the surface of the water. However, only a few feet below the surface that lightning strike has very little effect because the heat doesn't penetrate and the electricity disperses to the cube of the distance from the strike point. This is why you don't see masses of dead fish after lightning hitting a lake or river.
So if magical lightning works like real lightning in your game, it would be largely ineffectual when used underwater.
Just use the spell as-is. I’ll point out a line from the ‘24 DMG:
Rules Aren’t Physics. The rules of the game are meant to provide a fun game experience, not to describe the laws of physics in the worlds of D&D, let alone the real world.
Do you really want to start measuring the effects of lightning in fresh water vs salt water? What about thunder damage, as sounds travels differently through water than it does air? Does the poison from poison spray just dissipate harmlessly in the water?
It just opens a real can of worms that, imo, doesn’t actually make the game more fun.
I think that ultimately depends on the group, and I was coming up with a base to use for this particular table as they like to discuss physics. Having a plan out the gate for the future will just save a lot of side conversations that distract not only me, but the other players as well.
Wouldn't they fry themselves?
Is this a player-initiated version of "rocks fall, everyone dies"?
But yeah, I agree with Xalthu.
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It kind of is. At this point I've told them they can send me what it is they would like to use and I will get them underwater mechanics for those things or they can use them as written.
Thunder damage is, I think, the only one that realistically would deal more damage underwater than in air. Though for sound it's pretty unclear since different frequencies travel differently in water vs air, but I always imaging thunder damage as a thudding base noise which would travel well in water. Fire is already halved RAW, lightning would become emanations with the damage cube-rooted, force is unaffected, radiant would be slightly reduced since most water blocks light more than air does, necrotic would be unaffected,..
Cold... hm.. cold is an interesting case. Water's extremely high heat capacity that causes fire damage to be halved should really also halve cold damage. Though if the cold is so cold as to freeze the water then it should impose movement penalties on its wet victims.
Acid should be completely ineffective since it would instantly dilute and get buffered by the bicarbonate dissolved in water.
Aquatic creatures should maybe have vulnerability to poison since the (relatively) low amount of oxygen dissolved in water means most of them have greater permeable membranes to absorb dissolves gases / nutrients in the water. Certainly amphibians are very sensitive to toxins in their water. Not sure about this one though, air-breathing creatures also need lots of permeable membranes to absorb oxygen effectively into their water-filled bodies.