When using magic to conjure flames do the flames create smoke even when they are not burning anything?
To me the logical answer is no, since the flames are not consuming anything and smoke is generated by the partial burning of fuels. That however is a very modern reasoning.
Could it be the case that in the world of ArM smoke is simply the byproduct of fire, fuel or not?
It seems to me that smokeless flames have a much more magical feel and also generally increase the viability of using magically conjured fire to heat/light things. Since smoke would create lots of problems with indoor fires.
I was under the impression that smoke was under Auram, being an atmospheric phenomenon.
So CrIg should not directly make smoke. However, individual casting sigils could cause smoke as a side-effect?
Even natural fire does not necessarily produce smoke; smoke is the result of incomplete burning. Ideal fire is smoke-free, and magical fire is supposed to be ideal (more or less), is it not? It seems fair to require either an auram requisite or the ignition of a natural fire to produce smoke.
Different fires made very different amount of smoke, so the medieval paradigm, I think, would know a better fire creates less smoke. As mentioned, magic makes the ideal fire, so I think a smokeless magical fire does meet the medieval paradigm.
I'd say you don't see smoke coming from a CrIg flame itself (a Pilum of Fire doesn't leave a trail of smoke where it passes), but a Coat of Flame does generate smoke because the target is being burnt. The spell is magical, but it's effects are very much mundane (things that burn will burn in the normal way; on that note, you do see smoke coming of the body of someone hit by a Pilum of Fire).
You would have, I believe, "degrees of completeness" for the combustion. A higher guideline for CrIg is more perfect, generating more heat and less smoke (just as you need a higher magnitude of CrCo if you want higher stats). As such, a Base 5 Coat of Flame generates more smoke than a Base 25 Coat of Flame.
How much more? That depends on the target. Oil generates more smoke than paper.
If needed you can add PeAu requisites to your spell to destroy smoke.
The question of whether magical fires generate smoke boils down to the question of whether the medieval era understood that smoke was generated by stuffing burning down and not the fire itself. I think they would have. It's not exactly rocket science to notice that if you add fuel to a fire, the smoke volume increases and may change color. I think this is likely to have been noticed very early on, after all, pyromancy - the study of the smoke behaved after you threw things in a fire - was a divinatory art used in ancient Rome.
Djinn in ancient parlance were described as being spirits of the smokeless flame. Alcohol burns without smoke if it is pure (though at the same time pure alcohol would have been unknown in the middle ages) and of course a number of things burn with smoke that is not visible. As such it is pretty clear that it was known that fire did not have to produce smoke, though an interesting aspect of this is that for various reasons fire tends to produce more smoke in cold weather, so the distribution of that understanding might not cover the whole of Europe.
The point on sigils is well taken, and is likely the best indicator, given that fire could go either way and it is not clear how widely it was believed that one was more natural that the other- in honestly it was an issue that most in Medieval Europe probably gave no thought to at all. A few wisps of smoke might be the "middle condition" for a typical casting.
They knew that smoke depends of woods and another fuel, not fire. They knew how change a smoke with some addition to colore it, for instance.
If CrIg creates a fire without smoke. May I involve that, to create a fire with smoke (for communication for instance), I would use CrIg with Auram Requisite ?
Alchemists certainly knew this, I don't know that the average person of the period would. Even with that knowledge being able to change something does not indicate its origin- the right herbs can change the way a person acts and how they see the world, but this does not mean the human mind springs from herbs- the fuels that change the color of smoke may well contaminate the smoke without having to be the cause of smoke. The fact that there are fires which produce no (visible) smoke would be a much stronger support than changing the nature of smoke, but again these are rare.
I suppose the strongest influence, if one were to pose the question to someone in the middle ages, is that fact that the sun (which is clearly fire) does not produce smoke.
Historically, the knowledge and uses of fire that produces different amounts of smoke is ancient. Which woods produced the most and best smoke for smoking meats was something learned since back when humans were still cave dwellers (far further back than actual age of the world in ME). Smoke signals as a form of communication, with the Greeks actually designing a version that could send "plaintext" messages.
On the opposite end of the scale, fires which produced as little smoke as possible were an important survival tool when traveling through any "hostile" area. Even a properly built fire which prevents its light from being easily seen gives away your general location if there is obvious smoke.
So humans had knowledge that burning different things in different ways produced different quality and quantity of smoke (from almost none to extremely dense) since ancient times. Both ends of the scale would see extensive use throughout ME, ranging from wanting as little smoke as possible within buildings and when traveling to high amounts of "clean" (meaning low in resins and oils) when smoking foodstuffs. This knowledge would be possessed by a much higher percentage of the population than today, since it was the means of the day for light, heat, and cooking.
The people of ME would know that what you burned and how you burned it would determine the smoke produced. That is, the fuel and not the fire determines the smoke. Therefore pure magic fire that is not burning anything should not produce any smoke. However as soon as that magic fire begins burning something, there will be smoke based on what it is burning.
So when you cast some CrIg spell, there will be no smoke until it strikes and begins burning its target.
I would leave it up to the caster, either at time of casting or when they develop the spell. A pilum of flame with no smoke is fine as is one with a big grey-black trail.
In Aristotle's Meterologica, smoke is a combination of fire and air, which results when fire is added to wood (primarily earth and air). The fire liberates and mixes with the air from the wood to form smoke, leaving behind the earth (=ash). i.e. (Earth+Air) + Fire -> Earth + (Air+Fire)
My feeling is that smoke only therefore results when something is burned with magically-created fire. Where there is fire there is not always smoke; but where there is smoke there is always fire.
Unless the fire combines with free air in some way- perhaps this only happens when the air is exceptionally cold? Or of course if the sigil warrants it...
