Sky Isles Organization

Sky Isles are arranged in a very odd way, on that makes it difficult for most to understand. Due to the constant slight shifts of the map, no position of any isle is truly static. In addition, a problem land does not have is the height of each Sky Isle. Generally, Sky Isle establishments are located in the same general belt, called the Habitable Zone. Any higher distance up, and many health problems arise for most races, as well as increasingly hostile wildlife.
Above a certain limit, Isles are regarded as Upper Isles. These isles, while not as hostile as those outside of the Habitable Zone, are still colder and harsher on living things. Very few land crops grow here, and snow and icy clouds will settle over towns for days. These isles are much less traveled, and generally self sufficient, sometimes forming coalitions among themselves for shared prosperity. The advantage to these isles is that they are much larger, as they collide less often with others. Because of the wide range of the isles, furs, hunting and what little mining Aerava has is done here.
Within a certain middle area, these are considered Middle Isles. These Isles are what most of the population of Aerava live on, and are the essential places of learning, trade, and growth of the entire realm. Generally, these places share little in common, as this is the most wide-ranging region by far. Generally, efficient agriculture, densely populated city centers, and large amounts of Sky Driver trade occur here, allowing the whole of Aerava to prosper.
The Lower Isles are more populated than the Upper, but much less so than the Middle. Much warmer and wet, due to being above very few clouds, Lower Isles that are unpopulated resemble the rainforests of Terr'Aina . The ones that are populated, provide the necessary Sky Driver ports that allow interrealm trade, especially from less efficient Kaiyocean and Terr'ainan Sky Drivers. They also have much more exclusive luxury goods, such as coffee, exotic fruits, and hard-to-get spices. 
Beyond simply Upper, Middle and Lower, there exists whole classifications of Sky Isles based on how high, what general environment they contain, and their general relation to the other isles. However, this information is better left up to the cartographers who must remake their maps yearly.

Type

Natural