[Fantasy] Help with Strange Weather

[Varyon]

I have some (what I think are) interesting ideas for the weather of a fantasy setting, but I don't really have the sort of background needed to puzzle out all the effects, or how they should be handled. Fortunately, many of you do have such backgrounds, so I cast my questions to you, good forumites.

Sun

The sun, such as it is, in this setting is not a star or anything of the like. Rather, during the hour of Dawn, a luminous gas begins to bubble from the eastern sea, causing the horizon to slowly lighten. At the end of Dawn, Sunmake (I probably need a better term) occurs - the gas coalesces into a shining orb, producing heat and light. The orb then arcs over the (more-or-less flat) world, losing potency as it goes. Near the surface of the western sea it undergoes Sunbreak (again, probably need a better name), where the orb shatters and becomes simply a luminous gas again. This gas slowly sinks into the sea during the hour of Dusk, leaving the only light as that of the stars and moon (which produces its own light, rather than reflecting that of a proper sun).

Obviously, this whole process is supernatural, so I don't need any explanations on how/why it happens. I would, however, like some advice on the effect this would have on the world itself. The "Sun" is both bright and hot, so it seems to me that when it forms (and sets) the seas immediately near it would boil into steam, and any land nearby would probably be desert. As it loses potency as it travels, however, it seems to me that you'd end up with some sort of gradient - too close would be burnt and lifeless, then you'd get something more tropical, then subtropics, then something more temperate, then possibly something polar, then (as the sun begins its descent and gets closer) narrower bands of temperate, subtropical, tropical, and desert. Distance from the equator-equivalent would also matter, however - the further to the north or south you get, the colder it's going to be. Such a complicated set of climates is somewhat beyond me - does anybody have a clue as to what such a world would look like?

Mist

Another idea I had, based partially on the antediluvian "water canopy" theory and partially on Brandon Sanderson's Mistborn novels (and that I came up with while misting some plants in the garden), was to have the world's precipitation occasionally replaced by Mist. That is, when the dice indicate rain or snow for the day, a second roll can serve to replace this with a fine vapor. Mist isn't actually water vapor, and distorts light and sound without reflecting or absorbing it. Mist does deposit water on surfaces. This is beneficial in the spring and summer, when it serves to water plants without the destruction that can occur with rainstorms, but in the fall can result in a deadly chill - and in winter a man who finds himself far from shelter when Mist comes may well freeze to death within a shell of ice that forms over his body. Mist forms and mostly stays outdoors - it will leak into a building or cave through open doors, windows, etc, but unless the area is small or riddled with holes will dissipate a short distance in.

With Mist being supernatural, I intend to allow for at least some special abilities to interact with it and/or require it. Tentatively, those with such abilities (and the abilities themselves) would be called Mist Touched. Most are easy enough, as they would simply have a Mist Touched Limitation worth -60% (Mist only occurs outdoors, which is -20%, and is present less than 6% of the time, qualifying it for a -40% from Accessibility). The two that are giving me some trouble, however, are Mist Eye and Mist Ear. As noted above, the Mist distorts light and sound, but all the information still reaches the senses. This results in up to a -4 penalty to Sight and Sound Sense rolls (the penalty cannot exceed half the Range penalty, round against the character). While you technically still see and hear the sights/sounds, they are often so distorted it's impossible to tell what they are - if the penalty makes the difference, the character thinks they saw/heard something, but it was too distorted to figure out what, if anything, it was. I want Mist Eye and Mist Ear to be leveled Perks that negate the penalty out to a certain range. The problem is, I don't know what range is appropriate for each level of the Perk. Characters who opt to pick up Acute Sight and/or Acute Hearing with the Mist Touched Limitation have the value of that Limitation boosted to -80%, but it only works within the range of their Mist Eye or Mist Ear Perk. That is, if a character has Mist Eye (20 yards) and Acute Vision 5 (Mist Touched -80%) [2], said character is at +5 to Sight rolls within 20 yards. Beyond this, however, he loses the benefit of both Mist Eye and Acute Vision - at 30 yards, he's instead at -4. Visually, this looks to the character like a thick wall of Mist at 20 yards out.

My other issue with Mist is that I'm not certain what sort of effects essentially being in a light rain for several hours should have (Mist sticks around for an average of around 8 hours). The advent of Mist slightly changes the ambient temperature (it gets a little cooler if it's warm, a little warmer if it's cold), and the water itself forms at whatever the ambient temperature is - meaning when you're stuck out in 10 degree (Fahrenheit) weather, the Mist deposits ice. How should this be handled for characters traveling through the Mist?

[Nereidalbel]

Either the eastern sea isn't actually water, or, the sun doesn't boil it because magic. Anything living too close to where it rises is probably incredibly resistant to heat, though.

For the Mist perks, I'd base the range on the character's Per, and allow another perk to increase their range.

Anybody stuck in Mist below the freezing point of water is either going to find shelter, have hydrophobic clothing (oil, technology, or magical), or die. Does Mist prevent fires?

[Desthro]

To answer the questions a little more firmly, the cosmology of your world would be quite a big help. If the world is "more or less flat" how do the seas not run dry by bleeding away into space? How is the atmosphere retained? Is it a "bubble" of order in an otherwise chaotic world where there is a very real barrier that keeps everything in? Is there a world on the other side like in the World of Xeen? (Might and Magic 4 and 5 I believe. I think I might have found my next campaign idea. . . thank you!) Do the seas flow from one side of the plane to the other? Does it matter?

Regarding the "sun" since it is supernatural, it depends on the scale of your world. How wide across is it? What weather patterns are there? If it is supernatural why are we trying to model weather patterns and the effects a supernatural heat and light source has on the world? If you don't need to know how the "Sun" works, you most definitely don't necessarily need to know what the effects are and can just model them however you like according to your whims. Unless the "Sun" really is an illusory thing and nobody has ever sailed out far enough to find out what REALLY happens when it rises and falls.

Regarding the Mist, I think this is a really neat and clever alternative weather pattern. I've been in freezing mists before while hiking on mountain tops, and while it is relatively unpleasant, (ice in your beard sucks...), I wouldn't say it was any different than handling the rules for exposure in the basic set already. (IE being wet AND cold.) The ice won't get deposited quickly enough to be a significant threat of binding you up, though that might be different in your world.

[evileeyore]

Originally Posted by Varyon

Mist forms and mostly stays outdoors - it will leak into a building or cave through open doors, windows, etc, but unless the area is small or riddled with holes will dissipate a short distance in.

I'm monetarily enamored with the idea that the mist is driven back by fire or love... that a home with a blazing hearth or a loving family can keep the freezing mists at bay, but empty castles or hate filled homes can fill with it.

My other issue with Mist is that I'm not certain what sort of effects essentially being in a light rain for several hours should have (Mist sticks around for an average of around 8 hours).

Ya get wet?

Down here in extremely humid and sunny Florida the dampness in the air compounds the heat. It just sucks the will to live right out of you. So perhaps the Mist simply compounds Fatigue lose due to inclimate weather?

How should this be handled for characters traveling through the Mist?

The same as being in a rain or snow storm (or torrential downpour or blizzard prehaps). Visibility is shot, and you need cover from the weather.

[Varyon]

Originally Posted by Nereidalbel

Either the eastern sea isn't actually water, or, the sun doesn't boil it because magic. Anything living too close to where it rises is probably incredibly resistant to heat, though.

It's water, and it boils. At least, that's the current plan.

Originally Posted by Nereidalbel

For the Mist perks, I'd base the range on the character's Per, and allow another perk to increase their range.

Stinks a bit too much of double dipping to me. I was leaning more toward the first Perk letting you see out to 10 yards, then 500 yards, then 2000 yards, and so forth (although 2 or 3 levels is probably sufficient if you don't also have some sort of Telescopic Vision).

Originally Posted by Nereidalbel

Does Mist prevent fires?

Nope. You'll have issues getting one going - everything is wet - but once you've got a solid flame it will push the Mist away slightly. Candles and unshuttered lanterns would probably get smothered out, however.

Thinking further on this, I think I've got a good idea on what effects Mist would have on fire starting. First off, you need either a tinderbox (to keep Mist from the tinder while you're lighting it) or a method of getting the tinder lit quickly. With a tinderbox, you have up to 1 minute to get the fire going - take more time than this and your tinder gets too wet and any small flame you've got going goes out. Without a tinderbox, you've only got 15 seconds to get a fire going. Base fire starting times are doubled, as normal for wet materials. Thus, starting a fire in the Mist requires flint or a fire piston with a tinderbox or sulfur matches without one. Failing that, you may be able to get away with using Haste to speed things up.

Originally Posted by Desthro

To answer the questions a little more firmly, the cosmology of your world would be quite a big help. If the world is "more or less flat" how do the seas not run dry by bleeding away into space? How is the atmosphere retained? Is it a "bubble" of order in an otherwise chaotic world where there is a very real barrier that keeps everything in? Is there a world on the other side like in the World of Xeen? (Might and Magic 4 and 5 I believe. I think I might have found my next campaign idea. . . thank you!) Do the seas flow from one side of the plane to the other? Does it matter?

The world's still a work in progress, but it's essentially a flat-bottomed bowl. There are massive mountains in all directions that keep the seas from flowing away. The "moons" follow a strange orbit, moving slowly when beneath the world and more quickly when they are visible to the inhabitants - the way it works out, each of the five moons is visible for a season (the world has 5 seasons), slowly making its way across the sky. Once one moon dips below the mountains, the next rises from the other side (like the sun, the moons go from east to west), and the cycle repeats. There are no plans for any sort of world on the other side, or indeed of anything interesting existing outside of the world itself. I'm not certain how this matters, but there you are.

Originally Posted by Desthro

Regarding the "sun" since it is supernatural, it depends on the scale of your world. How wide across is it? What weather patterns are there? If it is supernatural why are we trying to model weather patterns and the effects a supernatural heat and light source has on the world?

The Sun is supernatural in origin, but not (necessarily) in effect. It produces sufficient heat and light to warm the world and allow plants to grow. The moons also probably generate some heat to prevent the world from freezing between Sunbreak and Sunmake, as there is no "hidden" sun to keep things warm as on Earth.

As for weather, I've only got that worked out for the primary region of interest. As noted above, the world has 5 seasons, and each of these is broken into two months (although I need a better term than month, as that's more appropriate to a season - which has a single moon - than a month - which is either while the moon is rising or while it's falling).

Partum (Spring) is cool to warm with 14 hour days and 10 hour nights, and it rains on a roll of 1-3 on 1d (each rain lasts an average of 4 hours). Rains are light in Primus (when most planting is done), heavy in Secondus (with occasional violent storms). Auctum (Summer) is warm to hot with 16 hour days and 8 hour nights, and it rains on a roll of 1, 1-6 or 2, 1-3 on 2d. There's no real difference between Tertius and Quaterus, but most spend the first repairing any damage caused by the storms of secondus, the second supplementing their dwindling rations by hunting. Meterum (Harvest) is comfortable with 12 hour days and 12 hour nights, and it rains on a roll of 1 on 1d. Quintus is when the harvest occurs, and Sextus is spent preparing the harvested food for storage. Corrum (Fall) is cool with 10 hour days and 14 hour nights, and it rains on a roll of 1,1-3 on 2d. Septus (and indeed Corrum in general) is the primary time for warfare, as it's cool without being freezing and the army has plenty of rations to march with (and can capture large stockpiles of enemy rations). Octus involves slaughtering nonessential livestock and preparing to hunker down for the coming cold. Mortum is cold with 8 hour days and 16 hour nights, and it snows occasionally. 1,1-5 on 2d starts a snow, which persists for an average of 7 days. 1,6 starts a blizzard, which lasts for an average of 4 days.

Above, "day" is defined as the time between Sunmake and the final dissipation of light following Sunbreak, "night" is between this dissipation and Sunmake. In-world, people think of "day" as being the time between Sunmake and Sunbreak, "night" as when there is no light aside from the moon, and "dawn" (the hour leading up to Sunmake) and "dusk" (the hour following Sunbreak) are their own thing.

Originally Posted by Desthro

If you don't need to know how the "Sun" works, you most definitely don't necessarily need to know what the effects are and can just model them however you like according to your whims. Unless the "Sun" really is an illusory thing and nobody has ever sailed out far enough to find out what REALLY happens when it rises and falls.

Still working on scale, but the sun is a real thing - and it would likely incinerate anyone who journeyed out to meet it. My statement was meant to be "I don't need any advice on how the sun forms and breaks," but I see the way I wrote it implies "I don't care how the sun forms and breaks." The question is, given the information provided (that an orb of heat and light forms and arcs over the land every day), what sort of temperature patterns (and other effects, such as wind and waves) are we likely to see?

Originally Posted by Desthro

Regarding the Mist, I think this is a really neat and clever alternative weather pattern. I've been in freezing mists before while hiking on mountain tops, and while it is relatively unpleasant, (ice in your beard sucks...), I wouldn't say it was any different than handling the rules for exposure in the basic set already. (IE being wet AND cold.) The ice won't get deposited quickly enough to be a significant threat of binding you up, though that might be different in your world.

Ah, that's useful information. As my weather system cleanly differentiates between snow and blizzard, I think I'll have mist that replaces snow be of the more mundane freezing mist/fog variety, while mist that replaces a blizzard will be a sort of "Death Mist" that actually can - and will - entrap a man in ice and freeze him to death. I think I'll have this variant impose CP (from Technical Grappling) every minute or so, ignoring most CR. I'm not certain how much it should impose, or how to handle Break Free attempts (I'm thinking you'd be mostly reliant on your core, so you'd probably be at around 30% or so of Trained ST). I'm currently leaning toward an exploding 1d (well, kind of exploding; each time you roll maximum, you roll another 1d-1 and add the result) and Break Free is handled normally, albeit at 30% of TST. The mist actually resists the Break Free attempt as though it had Parry 10. That sort of exploding 1d gives an average of around 4 CP, and a character with TST 10 (reduced to 8 for CP, then 2 or 3 for 30%) will average 1/6 points on an average hit. Assuming he always hits but doesn't go Deceptive, he'll lose an average of 48 seconds every minute to fighting off the mist.

[Varyon]

Originally Posted by evileeyore

I'm monetarily enamored with the idea that the mist is driven back by fire or love... that a home with a blazing hearth or a loving family can keep the freezing mists at bay, but empty castles or hate filled homes can fill with it.

As noted above, Mist is driven back by fire, but I don't want it to have any sort of moral/emotional connection. I also want it to be possible to find shelter from it when out in the wilderness, thus it simply will not enter into a more-or-less enclosed area - be it an abandoned castle, a shack in the woods, or a convenient cave.

Originally Posted by evileeyore

Down here in extremely humid and sunny Florida the dampness in the air compounds the heat. It just sucks the will to live right out of you. So perhaps the Mist simply compounds Fatigue lose due to inclimate weather?

Mist is more like rain than humidity, so it should serve more to cool you down than to make you die of heat.

...

I've decided the situation outlined in the first post doesn't quite work like I'd prefer. First off, the Sun doesn't lose heat and light as it travels - that was under an initial plan to have the Sun form, then arc across the sky until it was all burned out, but once I abandoned that idea and made Sunbreak a thing, losing heat and light is just an unneeded complication. Secondly, I originally had the Mist still transmit all light both as a way to justify Mist Eyes and to prevent the Mist from potentially blocking out the sun for long periods of time. This isn't necessary, however, as the Mist is a supernatural thing that some can actually draw on for power (the Mist Touched have their abilities explicitly powered by Mist, and I'm thinking of having a Mistcaster Advantage that would let mages be able to power their spells using the Mist as well). Mist instead blocks light much in the same way as normal mist would, although I'll maintain the progression from the first post (where it gets worse with range). So, a character with Mist Eyes is actually drawing on the power of Mist to see through it, and plants are able to use Mist to fuel their photosynthesis - in fact, being in Mist helps them grow faster and have higher yields (which is necessary, as the growing season is only a few months and there is only one of them, rather than the two we have on Earth).

[jason taylor]

Originally Posted by evileeyore

I'm monetarily enamored with the idea that the mist is driven back by fire or love... that a home with a blazing hearth or a loving family can keep the freezing mists at bay, but empty castles or hate filled homes can fill with it

That is actually kind of cool. Is the mist sapient?

[Terwin]

Originally Posted by Varyon

It's water, and it boils. At least, that's the current plan.

Water transmits heat roughly 10x better than air, so if the sun is within the sea for more than a few minutes, then sea-water will be pretty hot for most of the day, especially with a sun that is hot enough to cause living flesh to burst into flame from mere proximity.

Originally Posted by Varyon

The world's still a work in progress, but it's essentially a flat-bottomed bowl. There are massive mountains in all directions that keep the seas from flowing away. The "moons" follow a strange orbit, moving slowly when beneath the world and more quickly when they are visible to the inhabitants - the way it works out, each of the five moons is visible for a season (the world has 5 seasons), slowly making its way across the sky. Once one moon dips below the mountains, the next rises from the other side (like the sun, the moons go from east to west), and the cycle repeats. There are no plans for any sort of world on the other side, or indeed of anything interesting existing outside of the world itself. I'm not certain how this matters, but there you are.

The orbit is not that strange, it is just highly eccentric with the lower altitude part(and thus the faster moving part) where the moon is visible, you could even have all 5 moons in the same orbit, just at different points of that orbit.

Originally Posted by Varyon

The Sun is supernatural in origin, but not (necessarily) in effect. It produces sufficient heat and light to warm the world and allow plants to grow. The moons also probably generate some heat to prevent the world from freezing between Sunbreak and Sunmake, as there is no "hidden" sun to keep things warm as on Earth.

no need for moon-heat, a lot of atmospheric thermal inertia is due to humidity, Humid air gets heat back when some of that water condenses(giving up the heat that made the water go from liquid to gas). This is why in deserts it is very hot in the day, but water can freeze at night, no humidity to condense out and slow the transition.

Originally Posted by Varyon

Still working on scale, but the sun is a real thing - and it would likely incinerate anyone who journeyed out to meet it. My statement was meant to be "I don't need any advice on how the sun forms and breaks," but I see the way I wrote it implies "I don't care how the sun forms and breaks." The question is, given the information provided (that an orb of heat and light forms and arcs over the land every day), what sort of temperature patterns (and other effects, such as wind and waves) are we likely to see?

With all that steam being generated when the sun rises and sets every day, I would expect lots of rain over the ocean and shores as the evening air cools back down each night.

The rising hot air from the area of the sun would cause cool breezes to flow towards the sun when it is low to the ground in the morning and evening(probably helping all that evaporated water spread further inland after sunmake and sunbreak)

With that hot orb near by in the sky heating up the air, I would expect very little in the way of day-time precipitation and clouds would likely be a 'mostly at night' type of thing as the air cools back down.
(clouds rely on cooler air up high where the rising air condenses out much of it's humidity as clouds when it gets too cool to keep it as water vapor)

[Varyon]

Originally Posted by jason taylor

That is actually kind of cool. Is the mist sapient?

In world, people (scholars, clergy, and laymen) are torn as to the nature of the Mist. Is it intelligent? Is it hostile, or friendly - or does its mood change with the seasons? Is it sent by a god of some sort, or is it the result of mortals interfering with magic?

The truth doesn't really matter to the setting. My current leaning, however, is that the Mist isn't sapient at all, and is simply a (super)natural phenomenon.

Originally Posted by Terwin

Water transmits heat roughly 10x better than air, so if the sun is within the sea for more than a few minutes, then sea-water will be pretty hot for most of the day, especially with a sun that is hot enough to cause living flesh to burst into flame from mere proximity.

True enough. From this I'm thinking that, at the world's "equator," there exists a sea that is mostly cut off from the rest of the world's waters (there would exist a few "streams" flowing in from the surrounding ocean(s)). It would be dogbone shaped, with one end being the place of Sunmake, the other the place of Sunbreak, and the middle being the area the sun passes over in its daily journey. This Sun Ocean would be surrounded by a strip of land mimicking its shape (so, dogbone shaped), and this continent would be surrounded by mountains (there are tunnels through them that the streams flow through), keeping the steam in so that, when night falls, it cools and causes rain to fall, which in turn cools the sea back down. The sun would likely form - and break - just above the tips of the mountains so that it's visible to the inhabitants. The continent would probably be barren and devoid of life, or it might be home to some bizarre fungi that grow rapidly during the night (perhaps they are obligate Mistovores, and the "steam" formed by the sun boiling the ocean is functionally the same as Mist) and are burned away during the day, leaving behind hardy spores that sprout again in the night. Such fungi might occasionally be found outside of this continent, as the spores are exposed to Mist and sprout into fruiting bodies. When the Mist dissipates with no subsequent heating to destroy the bodies and make them create more spores, it usually simply dies off and begins to decay, but sometimes...

Travel from the northern half to the southern half of the world would be interesting at the very least. Without an airship (haven't yet decided if those exist), you'd need a skilled crew to sail into one of the tunnels through the mountains, dropping sails and relying on the current to pull you down to the Sun Ocean. Once you're there, you'd need to use oarmen or a similar mechanism to reach an outlet on the other side, then you'd have to work against the current (perhaps the tunnels have paths on the sides, where you could hitch up some beasts of burden to pull you) to get out on the other side. This would have to be done at night, once the ocean has cooled off enough that your sailors don't collapse from the heat, perhaps surrounded by alien-seeming, glowing mushrooms.

Originally Posted by Terwin

The orbit is not that strange, it is just highly eccentric with the lower altitude part(and thus the faster moving part) where the moon is visible, you could even have all 5 moons in the same orbit, just at different points of that orbit.

The intent is indeed that all 5 moons share an orbit. Visually, the 5 moons are the same color (silver, like our own). The moon for Partum is a waxing crescent, the moon for Auctum is a waxing half, the moon for Meterum is full, the moon for Corrum is a waning half, and the moon for Mortum is a waning crescent. In-world, there's debate over how many moons there truly are, with just about anything from 1 (different faces/forms of a single entity) to 30 (thus 6 years being a full/holy year) being argued for.

Originally Posted by Terwin

no need for moon-heat, a lot of atmospheric thermal inertia is due to humidity, Humid air gets heat back when some of that water condenses(giving up the heat that made the water go from liquid to gas). This is why in deserts it is very hot in the day, but water can freeze at night, no humidity to condense out and slow the transition.

An excellent point. The moons do provide light, of course, but it looks like heat isn't necessary.

Originally Posted by Terwin

With all that steam being generated when the sun rises and sets every day, I would expect lots of rain over the ocean and shores as the evening air cools back down each night.

The rising hot air from the area of the sun would cause cool breezes to flow towards the sun when it is low to the ground in the morning and evening(probably helping all that evaporated water spread further inland after sunmake and sunbreak)

With that hot orb near by in the sky heating up the air, I would expect very little in the way of day-time precipitation and clouds would likely be a 'mostly at night' type of thing as the air cools back down.
(clouds rely on cooler air up high where the rising air condenses out much of it's humidity as clouds when it gets too cool to keep it as water vapor)

Intriguing. Looks like daytime precipitation and storms are going to have to be somewhat supernatural, which I'm fine with. In fact, it may be appropriate to state the "clouds" are actually Mist that forms high in the sky, with the sun often forcing them to break apart into normal precipitation.

[jason taylor]

It may matter to the setting if you want the PCs to wonder what it is.