Coriolis Effect

[Mystify]

I was watching some mythbusters the other day, and they were doing stuff with modern snipers. Apparently, at the range they are firing, they have to made huge compensations for a wide variety of factors. Among them is the Coriolis effect. For those unfamiliar with the term, its basically the earth rotating under your projectile, so your target is shifting from where you would expect. It makes it appear that the bullet curves to the side.
Depending on your D&D setting, you may or may not be on a rotating planet. I would assume that any moderate level ranged character knows how to account for the Coriolis effect, even if they don't understand its cause. Esp. if you have far shot.
So I thought it might be interesting to delve into the difference if the character finds themselves in a different environment, and thereby gain(or lose) the effects of the Coriolis effect. Lets say they grew up on a planet, and now find themselves on an infinite plane with no rotation. They shoot at arrow at something decently far away, and find that the arrow doesn't act the same way. Tell the player they expect the arrow to drift to the side, and it didn't. Give them a 1-time penalty on the attack roll. A competent archer should be able to compensate for the lack of drift easily, once they are aware of it. This should not be used as a way to arbitrarily penalize a ranged character, but rather add in a detail to the world.

[deuxhero]

The first arrow is guaranteed to hit a Shifter or Catfolk when it misses.

(admittedly, it would be a cool detail)

[Calanon]

I don't think life can exist on a planet with no Coriolis Effect, If i remember correctly doesn't the Coriolis effect only exist because of the Dynamo Effect? (Which is why even if there was an ocean on Venus there would be no Coriolis Effect, due to a lack of a Dynamo Effect) ...Maybe I'm over thinking things though... (Or am just plain wrong):smallconfused:

[TuggyNE]

I don't think life can exist on a planet with no Coriolis Effect, If i remember correctly doesn't the Coriolis effect only exist because of the Dynamo Effect? (Which is why even if there was an ocean on Venus there would be no Coriolis Effect, due to a lack of a Dynamo Effect) ...Maybe I'm over thinking things though... (Or am just plain wrong):smallconfused:

The Coriolis effect has nothing to do with oceans and very little to do with life as such. (It does affect atmospheric circulation, though.) Basically, it's just the result of being on a rotating sphere; Venus therefore already experiences it, as does the moon, the sun, and so forth.

In a D&D cosmology, there is no inherent reason for life to only exist on rotating planets, or even on planets as such.

[Calanon]

The Coriolis effect has nothing to do with oceans and very little to do with life as such. (It does affect atmospheric circulation, though.) Basically, it's just the result of being on a rotating sphere; Venus therefore already experiences it, as does the moon, the sun, and so forth.

In a D&D cosmology, there is no inherent reason for life to only exist on rotating planets, or even on planets as such.

Is there any correlation between the Dynamo Theory and the Coriolis Effect? I can't recall if there is... :smallconfused:

[Acanous]

Well technically your planet needs to have a decent ammount of Iron or other ferrous metal under the crust in order to maintain a dynamo effect. I'm not sure what the composition of Venus is (Have we ever *Actually* checked? I'm pretty sure we've never taken any core samples of *Any* of the other planets in our solar system, and use the "Best educated guess" system) but if it lacked Iron it could lack a Dynamo effect.

[Rossebay]

Well technically your planet needs to have a decent ammount of Iron or other ferrous metal under the crust in order to maintain a dynamo effect. I'm not sure what the composition of Venus is (Have we ever *Actually* checked? I'm pretty sure we've never taken any core samples of *Any* of the other planets in our solar system, and use the "Best educated guess" system) but if it lacked Iron it could lack a Dynamo effect.

We haven't checked, but certain elements give off specific wavelengths of light, so we can determine the presence of certain elements from long-distance.

But I've only heard of that to dissect the composition of things like the Eagle Nebula, not an actual object or planet.

[Calanon]

Lets not have this boil down to a Geophysics/Astronomy Discussion :smallannoyed:

A planet lacking a Coriolis Effect have any effect on the firing of an Arrow? and if it does what kind of penalty would you give the shooter?

As a Side Discussion does this mean that Father Lymric can potentially Destroy all life on the planet just as easily as the Atropus can? only more slowly and painfully to its inhabitants?

[Mystify]

It doesn't matter if there is or is not a Dynamo effect; even though it may be essential to life in our universe, if the D&D sun doesn't emit harmful rays that we need protection from, then no dynamo effect is necessary. Or there could be some magical protection in place of it.
The coriolis effect is an interesting detail to add because it is simply an emergent property of a spinning sphere, and is mostly irrelevant to the game. Invoking the lack of a dynamo effect to irradiate the earth and purge of life has a bit more of an impact on the overall workings.

[Mystify]

Lets not have this boil down to a Geophysics/Astronomy Discussion :smallannoyed:

A planet lacking a Coriolis Effect have any effect on the firing of an Arrow? and if it does what kind of penalty would you give the shooter?
At long ranges, it can cause the path of the arrow to deviate. I'd say its no more than a -1 or -2 penalty at the ranges a bow can reach. Effects like wind are much more relevant.

[prufock]

PHB weapon with the longest range: Heavy Crossbow.
Range: 120 x 10 range increments = 1200 feet or 400 yards. At this range, you're looking at around half an inch. Just assume this is factored into the -2 per range increment already.

[Mystify]

PHB weapon with the longest range: Heavy Crossbow.
Range: 120 x 10 range increments = 1200 feet or 400 yards. At this range, you're looking at around half an inch. Just assume this is factored into the -2 per range increment already.
Add in far shot and a distance weapon, and your variance will be higher.
And its not a matter of adding in an additional penalty due to the effect. Its a matter of being surprised when its not there.

[absolmorph]

PHB weapon with the longest range: Heavy Crossbow.
Range: 120 x 10 range increments = 1200 feet or 400 yards. At this range, you're looking at around half an inch. Just assume this is factored into the -2 per range increment already.
Indeed, I had assumed that things like this were part of the purpose of the penalties for range increments.
Of course, with Far Shot and a Distance weapon, the max range goes up to 3600 feet, or 1200 yards. What's the deviation from the Coriolis Effect going to be at that range? Also, how're you calculating this?

[Esgath]

What you are doing is basically annoy the mechanically weakest damage dealers in the game.

[Calanon]

What you are doing is basically annoy the mechanically weakest damage dealers in the game.

OH MY LORD! THIS THREAD HAS JUST BEEN SUMMARIZED INTO A SINGLE COMMENT! :smalleek::smalleek::smalleek:

[Mystify]

What you are doing is basically annoy the mechanically weakest damage dealers in the game.
Sure, because a 1-time -1 penalty is a big deal... Esp. since its on their first shot, which can easily afford a -1 penalty and still hit no problem.

[Siosilvar]

Sure, because a 1-time -1 penalty is a big deal... Esp. since its on their first shot, which can easily afford a -1 penalty and still hit no problem.

Then why bother applying the penalty at all?

[lesser_minion]

Then why bother applying the penalty at all?

If you don't think that the reason he already gave -- "it's a nice touch that makes things seem more realistic" -- is a valid reason to do something, then you're not actually going to agree with him no matter what he says, are you?

[Fatebreaker]

I think you'd have to throw in a lot more to make this worthwhile. A one-time -1 to hit penalty appears random and is swiftly forgotten. It doesn't contribute anything. If players have to compensate in a variety of ways throughout the campaign (or even receive unexpected benefits), that keeps a running theme rather than, "Hey, remember that one time you had that -1 to hit? Good times, man. Good times."

For example, you might have players make perception checks or wisdom checks or will checks or something to overcome the effects. The more successes they get, the less likely they are to be influenced in the future. Eventually, they adapt.

Some game systems feature alternate realities, demi-planes, or areas where perception is a lie or reality functions in unexpected ways. Those might be a good place to start looking.

[Siosilvar]

If you don't think that the reason he already gave -- "it's a nice touch that makes things seem more realistic" -- is a valid reason to do something, then you're not actually going to agree with him no matter what he says, are you?

I'm all for realism, except when it doesn't matter. A -1 penalty doesn't matter, so why put it in?

Obviously, the counterargument is "a -1 penalty doesn't matter, so why not put it in?", but I'm not of the opinion that adding a line of text to a houserule list or book or wherever it's going to be for something that doesn't have much effect is worth it. YMMV, but if you're going to add yet another rule to the bloat that is 3.5, it ought to be worth the bytes and/or paper it takes up and add something interesting to the game beyond the time it takes to read the sentence. -1 penalties aren't interesting.

[Rossebay]

I'm all for realism, except when it doesn't matter. A -1 penalty doesn't matter, so why put it in?

Obviously, the counterargument is "a -1 penalty doesn't matter, so why not put it in?", but I'm not of the opinion that adding a line of text to a houserule list or book or wherever it's going to be for something that doesn't have much effect is worth it. YMMV, but if you're going to add yet another rule to the bloat that is 3.5, it ought to be worth the bytes and/or paper it takes up and add something interesting to the game beyond the time it takes to read the sentence. -1 penalties aren't interesting.

Describing the ground probably doesn't matter, so why put it in?

The color of the game doesn't matter, so why don't we just make everything black and white unless described otherwise?

I mean, if you're going to go by the logic that minor fluff things don't really matter, why are you playing D&D? Enriching the playing environment is one of the most important things to be a fantastic DM. If you have all of the small things worked out to use in your head, it definitely makes for a cooler experience.

If you don't want to use it, then don't.

[Siosilvar]

-snip-

Unless it's interesting. Fluff is interesting. Fluff with tiny fiddly bits attached is more of a headache than it's worth.

[prufock]

Add in far shot and a distance weapon, and your variance will be higher.
And its not a matter of adding in an additional penalty due to the effect. Its a matter of being surprised when its not there.

But are people really using a crossbow at its max range? At that point you're taking hefty penalties to hit - the variance from the coriolis effect is probably negligible. And if D&D is based around a quasi-medieaval setting, I doubt anyone was aware of the coriolis effect at all.


Also, how're you calculating this?
I'm not, I'm just estimating based on tables for firearms. Crossbow bolts travel slower so I inflated it a bit. Though I'm sure we could find a formula with google for anyone so inclined.

[drew2u]

For example, you might have players make perception checks or wisdom checks or will checks or something to overcome the effects. The more successes they get, the less likely they are to be influenced in the future. Eventually, they adapt.

In the Quintessential Druid, they had rules for Druids adapting to new terrains via survival checks. Every day they make a check based off of a DC that decreases every day they spend in that area.
A modified form of that could be used for planar/planteary travel.

[CTrees]

Indeed, I had assumed that things like this were part of the purpose of the penalties for range increments.
Of course, with Far Shot and a Distance weapon, the max range goes up to 3600 feet, or 1200 yards. What's the deviation from the Coriolis Effect going to be at that range? Also, how're you calculating this?

1200yds is... quite a long shot. Wind, drag, and the sheer angle at which you need to fire something as slow moving as a crossbow are bigger effects, but... even magic crossbows are likely firing very slow quarrels, compared to the bullets fired at those ranges. However, once magic gets involved, it becomes impossible to even guess speeds, so calculating coriolis drift is impossible. I can tell you that it can be inches on a long range rifle shot.

[Mystify]

I didn't realize this would be such a polarizing topic.

[Yora]

To calculate it, you would also need to know exactly in what direction you are shooting. A shot straight north would be very different than a shot west north-west.

[Fatebreaker]

In the Quintessential Druid, they had rules for Druids adapting to new terrains via survival checks. Every day they make a check based off of a DC that decreases every day they spend in that area.
A modified form of that could be used for planar/planteary travel.

Yeah! Something like that would be a nifty way to show characters gradually learning to play by a new realm's rules.

I think the trick would be to find a couple of ways to highlight how the new location affects characters, and otherwise use a broad, vague system to give players the basic idea. Let fluff fill in the rest.

[OracleofWuffing]

I didn't realize this would be such a polarizing topic.
Groan!

To make matters worse, Sigil's the inside of a torus, so...

[Yora]

But that should not make a difference, if it spins like a wheel.

Unless the spin creates the gravity, but that would only work on about one fourth of the torus inside surface.

[erikun]

So, let's imagine a situation where the PC party follows an evil wizard off-plane to their hidden sanctuary. They take the time to be stealthy, avoiding patrol guards and remaining hidden. When they finally locate the wizard tower, the see the evil NPC hanging out on the top floor, visible through the small window there. After taking the time to buff up the archer, they take out their Mageslaying arrow and fire it into the room. One diceroll later, and they roll just enough to make it through the window and hitting the wizard. Then the DM speaks up, and...

"Sorry, but the world you are from rotates and thus has the Coriolis effect. Because this world does not rotate, it does not have the Coriolis effect and thus your character's attempt to naturally compensate for it gives you an additional penality. You miss the shot."

Do we really think this would be considered an "impressively realistic" decision by the DM?


Besides that, if the Coriolis effect is due to the rotation of the planet (as opposed to just its curvature) then the direction the archer fires in makes a difference. Adjusting for firing north would be the opposite of adjusting for firing south. So not only would the above situation make absolutely no sense (because the party could not locate north of a featureless flat plane, and thus would not attempt to compensate in the first place) but it means that the archer would need to know with direction is north with every long-range shot, or else potentially take double the penality with every shot.

[OracleofWuffing]

So not only would the above situation make absolutely no sense (because the party could not locate north of a featureless flat plane, and thus would not attempt to compensate in the first place)
"If you have 5 or more ranks in Survival, you can automatically determine where true north lies in relation to yourself. (http://www.d20srd.org/srd/skills/survival.htm)"

Huh. Wait, so that means... Oh gosh, I don't think I'm supposed to think about this. :smalleek: Wait that shouldn't matter because there is no pole but the ability doesn't require a pole it just happens automatically and oh gosh

[Voyager_I]

Sometimes, it's better just to leave well enough alone. This is probably one of those times.

Failing that, you could just skip the pointless penalties to one of the weakest character archetypes in the games and just spend a sentence mentioning how the arrow flies a hair differently than the character had anticipated, assuming they know which way North is.

[Namfuak]

Wouldn't the Coriolis effect not really be relevant at any range that a bowman in D&D could shoot? Even with far shot, you are taking penalties at ranges higher than 180 feet (assuming a heavy crossbow). Since you take a penalty for firing any longer than that, presumably this is one of the reasons already. The only way I could see it actually having an effect would be on a shot fired using Distant Shot, which explicitly says that you take no penalties for firing at any range, and since it's an epic feat I think it's safe to say that the archer is so good they can account for all of that stuff anyway.

[TuggyNE]

Yeah, I think it would probably be best to include it as pure fluff, if at all -- e.g., if an archer happens to narrowly miss a shot in an unusual environment, feel free to say "you forgot to account for the Coriolis effect!" but don't actually impose any mechanical penalties. Similarly, if that archer just barely hits, mention how the arrow's flight unexpectedly swerved a bit, turning what s/he thought would be a near-miss into a hit.