When water takes over the role of oil, it becomes the most important resource of all kind. And whoever controls it, controls the future of the world.
Water on Earth surface is nearly depleted due to the extensive consumption from Union.
To further extract water, Union decided to harvest water in the cloud by forcefully condensing water vapors.
Stratoreservoir design: https://www.artstation.com/artwork/BXRQYD
Stratoreservoir , a gigantic type of airship designed solely for this task, is capable of slowly condensing water vapor into liquid water through its front nozzles, and has a total liquid capacity over a billion gallon. Which is just enough water to supply the Union City for a week.
Stratoreservoir design: https://www.artstation.com/artwork/BXRQYD
Clouds are rare in this world due to the limited water presence. However, there are occasional small cloud formations in various places. That's why the Union established Department of Precipitation Control (DPC) to monitor every potential cloud formation event worldwide.
DPC room design: https://www.artstation.com/artwork/zPrqPQ
There are two DPC office builidngs, one for monitoring northern hemisphere and another one for southern hemisphere. When an operator detects a potential cloud formation, they immediately notify the nearest Stratoreservoirs to initiate the Water Extraction Process (WEP).
seat design https://www.artstation.com/artwork/QX5J9E
In addition to weather monitoring, the DPC is responsible for coordinating military assets to protect Stratoreservoirs during WEPs. In this world, Union is not the only entity in need of water.
Exile is a group of wasteland inhabitants who suffer from extreme droughts, relying on looting water from Union Stratoreservoir.
They justifies their action by claiming that Stratoreservoirs took away the rain water that belongs to them. (Which is true)
Exile airship designs: https://www.artstation.com/artwork/LRYQgv
Exile airship fleet usually assembles beneath the cumulonimbus clouds right below the Stratoreservoir, to avoid detection. Then, all airships (usually 100-200) launch their rocket boosters and fly nearly vertically, breaking through the cloud layer at extremely high speed while opening fire at the same time.
Exile airship designs: https://www.artstation.com/artwork/LRYQgv