This is a planet I made up! Those are the levels of its atmosphere and stuff. Btw it's pronounced like 'airth' get it? Cuz they live in the air... heheh...
Think of it liiike Skyworld sorta, because the people are angels
But the clouds are like, really dense, so the houses float on them like boats!
And beneath all those clouds... is a dangerous realm sort of similar to our seafloors
Except instead of weird fish, there are GIANT LEECH-SLUG THINGS and it rains a lot so they're on the prowl pretty constantly.
Also... the angel people live by hunting in the sky and fishing in the clouds. They have no soil so they can't grow stuff... but they still import things from other planets.