The World of Infinite Sky
Technology
The general level of technology is dieselpunk with a guide date of roughly 1930.
Luftum
Luftum is the fuel of civilization and the source of energy that ultimately powers all of humanity's innumerable gadgets and machines. It is extracted from the established root systems of the Ciela tree which extend deep underground. While the trees that once grew from these roots drew only small amounts of luftum from the earth, modern industry has incomparably greater thirst.
It has been proven that industrial scale extraction of Luftum causes landmasses to sink closer to the Sea of Storms, therefore cooling their climates. The smaller the landmass, the greater the adverse effects of Luftum extraction.
Luftum Torus
The oldest and most basic of luftum mechanics, the luftum torus is a ring-shaped container of luftum that is driven to rotation by some other mechanical force. When so "spun up", the luftum torus creates an anti-gravitational field inside of its circular area which in turn causes the load-bearing portion of a ship contained within the torus to levitate relative to the planetary core. The spinning process causes Luftum to disaggregate into oil, water and dangerously toxic cielite tailings.
Due to engineering requirements, there is a certain minimum size associated with a luftum torus required for it to be efficient and useful. This has shrunk significantly in the past century and a half but it's still a very rare ship that masses less than a kiloton at standard load.
Luftum Dynamo
The luftum dynamo is basically a torus that, instead of lifting a large object, drives a high mass working fluid – typically mercury – to produce mechanical or electrical energy. A typical modern ship's luftum toruses would all have a dynamo incorporated to produce power. While no luftum dynamo is nearly as efficient as a torus, it is the key technology that allows production of useful electrical or mechanical energy from luftum. So long as the torus itself is operational, a dynamo produces more than enough energy to keep the torus spun up.
Luftum Combustion Engine
The luftum combustion engine is a class of devices that burn highly refined luftum (cieline) directly to produce thermal energy. The newest type is the Electrolyzed Luftum Combustion Engine. The ELCE was developed and generally used for airplane propulsion though it now also sees use in high performance ground vehicles.
Meteography
Although the altitude of any landmass could change over time, Mean Altitude, much like our world's magnetic north, is still the most frequently used altitude reference. It is defined as the altitude matching the official indicator at Kirisame Observatory. While not useful to scientists for advanced work, it is simple and useful for virtually everything else, including aeronautical navigation. Mean Altitude is at the low end of the atmosphere's habitable band and matches up very well with estimations for the overall center of mass of all known land as a whole. Below MA, average temperature rapidly drops and turbulence becomes more frequent. Low altitude areas tend to be cold, non-specifically gloomy and will experience intense blizzards if they are low enough to be engulfed by swells from the Sea of Storms. Above MA, average temperature gradually increases, though altitude cooling dominates local temperatures over land. This means that higher altitude landmasses are more likely to be warm overall but mountain tops are still colder than low lying areas of the same island. Beyond 20-30km above MA, increased fuel requirements reach a significant level, stimying both commercial and military shipping.
Sea of Storms
The lower boundary of the habitable band, the Sea of Storms is an intensely cold atmospheric layer that rises to within 6km of Mean Altitude in winter and retreats to approximately 12km in summer. This is also approximately the altitude of the lowest known land. Land beneath a certain altitude would experience snow and ice buildup exceeding the rate of outflow from thaw and glacial drift and would inevitably be pulled into the Sea of Storms by a feedback loop of mass increase. Most ships want to have as little to do with this layer as possible but some vessels are designed to run in it. For those, the ability to shed ice and negotiate very limited visibility are essential.
The Tropics
The Tropics are a remote layer beginning approximately 40km above MA and continue upwards, ramping up in intensity as one ascends. While this layer can experience intense weather, the greater challenge to ships is producing the lift to get here in the first place. Fuel requirements for altitude increase at an ever greater rate the higher one ascends. A cruiser with weeks or months of endurance at MA could burn up its Luftum supply in a matter of days patrolling the Tropics. Hand in hand with the impact on fuel economy is a marked reduction in the amount of land the higher one goes. Landmass altitude is obviously correlated in some way with the amount of Luftum permeating it. Whether this wealth could be extracted from such remote locations is another matter entirely. Beyond a certain point, there is so little land and habitation that most ships simply aren't built to go there. As a related matter, extraction of Luftum from any landmass naturally lowers its altitude and therefore has a cooling effect on its climate. This has already occurred in some locales with disastrous results.
The Desert
At very high altitudes, water supply becomes a concern. While landmasses in the Tropics have plenty of water, humidity rapidly drops off beyond around 60km above MA and dredging for water with condensations nets becomes virtually impossible. What little land there is becomes increasingly harsh and arid. Some of the highest flying Luftum ships ever constructed were highly specialized tankers and colonial cruisers designed by Continental Powers to operate here. Today, this region of the sky is largely the domain of the airplane.
The Void
High above, beyond even the Desert is the Void. It is too high for even airplanes to reach.
Geography
The Continent
The Continent is by far the largest landmass in the known world. It has a temperate climate overall, though it was warmer in the past, and has seasons caused by regular atmospheric cycles. Nonwithstanding local variation, there is a slight trend for the land to slope downwards towards the west, thought to be the result of greater concentration of Luftum remaining within the mountains of the Pureland.
While humans have dwelt on most landmasses since prehistory, the Continent is the cradle of civilization. Continental cultures have initiated periodic waves of influence and colonization outwards and it is only recently that the balance of power has shifted in favor of their oldest former colonies. Above the usual political division between countries, there is a tradition of dividing the Continent into five cultural regions – the four cardinal directions and the centrally located Purelands.
Western Plains
The kingdoms of the vast Western Plains have been unified under the banner of an imperial Great King a few times in the past but found strength despite division during the Age of Luftum. It was in the west where the Luftum Revolution was felt strongest and the most powerful industrial economies and empires developed from countries such as the Kingdom of Jigash. They emerged victorious but greatly diminished from the Continental Wars, even splitting into multitudes of miniscule component states in some cases. Now, they wrestles at once with both stability and integrity of what they still hold verses the disconcerting notion of reunification in this time of crisis.
Overall the coolest part of the Continent, the Western Plains are heavily populated but face relatively cold winters, especially in the westernmost areas. Because of ice melts from East to West - the same direction most rivers flow - the central areas of the region are known for (and agriculturally benefit from) annual flooding.
Northern Peninsula
The Northern Peninsula is a land of many characters divided by small, forested mountain ranges that stretch apart from the mountains of the Pureland. The countries of this region are traditionally the most technologically advanced on the Continent, being the birthplace of both the Luftum Revolution and the Dreadnought, but were mostly caught on the wrong side of the Continental War. Once a stronghold of democracy, defeat has led to the collapse or crippling of the republics and constitutional monarchies, leading to a new breed of dictators. Reconstruction and revenge are foremost on the minds of the population here.
Southern Highlands
The Southern Highlands are a rugged but beautiful land of chasms, caverns, underground rivers and other natural wonders. The climate is pleasant (though a little damp) and mild through both summer and winter. The small countries of the South had their time in the sun during the Age of Sail but have struggled to find relevance in modern times.
Eastern Sky
The Eastern Sky refers to a roughly semi-circular archipelago adjoining the eastern shores of the continent, forming (along with the eastern shore of the Pureland mountains) a ring around the Great Gulf. Though made up of islands, the Eastern Sky is nevertheless traditionally considered a part of the continent. Always more attached to the skies than fellow continental inhabitants, states of the East had been at the forefront of naval technology and imperialism for millennia but has largely been in turmoil ever since the Great Collapse.
As a region of disparate isles, the Eastern Sky has the greatest extremes of altitude with warm subtropical rainforest isles that look down upon the Purelands as well as bitterly cold realms perpetually in the shadow of the Continent's girth.
The Pureland
The Pureland is a great mountain range that occupies the center of the continent. The Oracle's Mountain lies within it, surrounded by minor states. The people of the Pureland tend to emphasize their neutrality to the political turmoil around them but are well known for their sometimes extreme zeal. As such, they have mostly shunned heavy industrialization and are technologically and economically backwards as a result.
The Oracle
The seat of the Oracle lies within the dormant caldera of the Oracle's Mountain. It is not the highest of peaks, but its almost perfect cone is a striking and universally known landmark. The verdant canopy of the Providence Tree hides just beneath the mist shrouded rim. While the oracular tradition has spawned countless shrines with predictive services throughout the world, the Oracle (capital O) perpetually resides here.
Long ago, it was the Oracle that first developed Oracular script to transcribe results from prophetic trances and these eventually developed into Mercantic script and Storic script which branched off into all known forms of writing today. Aside from the usual vague prophecies and interpretable predictions, one of the most important powers of the Oracle was (and occasionally still is) to confer kingship. The Oracle has steadily lost credibility over the past millennia and is generally not considered to hold much sway in the political landscape of 11930.
Near World
The Near World refers generally to island realms separate from but fairly close to the Continent – near enough that regular trade has been taking place for centuries or more and often close enough for direct flight by airplane. The countries in this region are presently the most generally advanced in the world, having largely overtaken the moribund Continental Powers in effectiveness if not size. Some are former colonies while others are indigenous cultures that have managed to preserve their independence whilst biding their time until today.
Middle Reach
The Middle Reach is the vast halo of lands that have been known since the Age of Sail but only fell into practical reach with the development of Luftum ships. These were the stomping grounds of the Continental Powers during their latter heyday though how much sway they still hold so far out varies from case to case. While the dispersion of technology and wealth during the Age of Sail has benefitted some of these areas, they are more often poor, backwards and objectionable places to be.
Far Shores
Storied lands even in the modern age, the Far Shores are at the limits of reach even for ships powered by modern Luftum turbines. Here exist vast and fabled lands.