Air magic only used to decrease humidity and improve living conditions?

Question

I'm writing a world with an overall warm and very humid climate (Eocene-adjacent, although it does not have to be 100% realistic). Population is very low compared to Earth. Humans generally live in small, agricultural settlements; life is dangerous and hard because of the humidity, floods, tornadoes, overwhelming surrounding rainforest/jungle with abundant megafauna (going to take some liberties with 'unrealistically' intelligent predators) etc. This has hugely hampered societal progress.

One civilization has managed to drastically improve their standards of living through the use of air magic. I'm thinking their scholars are able to manipulate air in one specific way: They can change air pressure and decrease the humidity in the air directly surrounding their territories. This allows them to breathe easier, build bigger cities, have more dry ground to house armies, etc etc. They dispose of superfluous water molecules that are taken from the air by carelessly sending them far away, thus causing more high winds, tornadoes, climate havoc etc (a slight metaphor for our current egotistical 'use' of our planet).

This culture has become very dominant; they see themselves as an enlightened people surrounded by barbarians. They engage in a somewhat benevolent colonialism: they govern other communities by exerting military power, offering protection, trade goods and - to an extent - knowledge, in return for food crops and building materials. They fight the rebel 'barbarian' societies that refuse to submit themselves to this system. There is a light comparison in there with the Romans, because their economy relies in large part on the force of their military to extract food sources and materials from the surrounding colonies.

Now I'm faced with the question: if these scholars can deploy air magic, how likely is it that this would be their only use for it? In theory it could be a formidable weapon, would allow them to fly, create a vacuum around an approaching force thus killing them all at once, etc etc. But for society building and story reasons, I don't explicitly want to do that. For example, their army consists largely of foot soldiers.

Are there any feasible/reasonable explanations for why they would only (be able to) use this air magic to improve their own living conditions by altering air pressure and humidity?

Answer 1

The easiest explanation would be that they simply don't know how. Perhaps they don't have an equivalent to the scientific method and related systems for performing scientific testing and experimentation. Instead they simply discovered that putting magical element x and element y together in a specific configuration dries the air in a certain radius around it. In this case they would either not have had the idea that it could be expanded further yet, which to some degree makes sense, since "stuff is dryer" doesn't necessarily expand into "conjure storms at enemies". Perhaps they don't even realize that they're doing air magic, or what air magic entails. For example, at one point irl scientists believed fire was caused by a specific element with negative weight, which was what became fire, and, as negative mass, caused weight to increase as it burned and escaped the fuel (Phlogiston Theory).

(edit: Phlogiston is a bit of a bad example, and was theorized after the scientific method came about, and was more of an intermediate theory to discovering what was actually happening. A better example is probably Aristotelian physics, which had a lot of clever philosophy, but was also largely wrong, not backed up by any evidence, but stuck around anyway because for a while nobody bothered questioning the clearly smarter Greek philosophers.)

Aside from this, since you're using the Romans as an example, perhaps they did invent further and discovered proper air manipulation, but dismissed it as impractical, since they lacked the infrastructure (at that point) to make it more powerful and efficient. Something similar happened with the irl Romans, where someone invented a prototype steam engine, but it was dismissed as a curiosity, since they lacked the systems to get sufficient power out of it, while they had no economic need for it, since water mills, wind mills and slaves were far cheaper. This would be especially likely if a single person invented it, Their patron didn't see an immediate benefit in what was essentially a curiosity, and it was thus buried in some random scroll cabinet and forgotten or lost.

Answer 2

They use probability manipulation

They don't have direct control of the weather. They can tweak the probabilities of cloud formation with subtle nudges and tweaks and change the wind flow to change pressure. This can't change weather a lot from what the natural probability is and so war uses are tricky. If rain is 20% likely they can boost that to 95%, but they can't boost 1% to 95% and they can't make more inches fall than could naturally.

It requires a lot of very expensive and complex infrastructure

They can't just wave a wand and do it. They need complicated magical materials and spells that took decades to make. While they can use it to protect weather in their regions, it would be very expensive and risky to bring those objects to enemy territory. Foreign territories that they have civilized might get those things, but only once there was a large army of foot soldiers there to civilize the area.

Answer 3

Air is a widespread low density medium so it needs lots of small widespread magic working together to do anything useful.

This means it takes a long time to set up. You need hundreds or thousands of small devices mathematically precisely positioned in the region to be effective.

Such a system is useless on the battlefield and not portable, but as something permanent, it's fine. You might be able to set up a one-time-use tornado for defense of a specific location but it's not something you can setup quickly, months of work per use, and it will likely destroy itself so not common or econimcal either.

Since it has to be widespread, it is not portable so magic airships would either not be possible or things that need to only travel along managed routes, more like air trains than ships. Or they are are absolutely gigantic behemoths and thus extremely rare.

Since it becomes a question of scale they might be able ot make somthing like air powered guns for individuals but nothing big an flashy and nothing that couldn't be done with gunpowder. This could even be restricted to the ability of indivudal mages depending on how you want your magic to work.

Answer 4

They are building magical rain shadows

Normally the places behind a mountain range become very dry because mountains encourage precipitation on them keeping water from reaching the far side. This is called a rain shadow. Your Aeromancers can not move humidity from one place to another, but what they can do is magically create rain shadows by building magical structures that encourage the air to rain out between the sea and thier lands. This has a few natural consequences that will make it difficult to weaponize:

1. They need an infrastructure: these mages need to construct massive public works just to enact thier spells. So you can imagine your aeromancy culture having to build a line of rune covered obelisks along thier border to create these rain shadows. So, even if they could be weaponized, it would mean having to spend months building these monuments in enemy territory and then having to protect them waiting for enough rain clouds to come along while camping your army at ground-zero of the magical effect. So, they in no way can replace the mobility of an army of guys with swords, and could easily pose a greater risk to your own troops than to the enemy.

2. They can not direct the power of nature, just trigger it: The Obelisks can't take all the water in the air and turn it into a high powered water cannon or anything like that. All it does is lowers the local saturation point making water vapor turn into rain. So, while a 50 mile long line of Obelisks can cause a significant change in local whether patterns, no single spot in that area is going to be hit by any Earth shattering changes. Occasionally this will mean the Obelisks will trigger an extra tornado or something with a powerful local effect, but these events are determined by what the weather is already doing making targeting a specific spot with a tornado impossible to do by design.

3. It takes time: Even once these things are built, it would take months or even years to notice thier full effect. If you live near one, yes, you will notice heavier and more frequent storms. If you live behind one, you'll notice the drier weather, but trying to flood or desertify any enemy can't happen over night. It takes a long time of manipulating the weather for an ecosystem to collapse.

Answer 5

People move but the ground and plants don't.

If they invoke some magic to remove the air from some location then the people caught in this vacuum could run to where there is air before they pass out and die. If magic is invoked to pour rain on an advancing army in an attempt to get them stuck in mud, drowned, or whatever then with some quickness of thought and motion they can avoid the worst of it, put up umbrellas maybe, or something more intelligent that doesn't come to my mind right now to merely end up a bit winded and wet rather than drowned.

The fauna may be unusually smart but even that might not allow them to cross a moat created by carefully controlled wind and rain. The magic works to impede or scare off animals but not a barbarian horde that has more intelligence, as well as greater motivation, to cross that moat.

Another option is there's a power limit.

They can create a strong breeze that could divert a tornado headed for their village if they noticed it in time but not create a tornado that would knock men off their feet.