Cirrus
The Sky Barrier
Can be home to characters.
Cumulus and Nimbus pass the peak at predictable intervals each night and each day, and for a few hours, travel between Cirrus and the two cities is possible. Tourists flock to the cities during this time while goods are also loaded onto the clouds or unloaded from them. It's made Cirrus quite a busy town, in spite of the difficulties many Dextroluma (not to mention other species!) find in breathing its air.
Cirrus is also home to what could best be described as a 'climate dormitory'. Here, would-be visitors to Cumulus and Nimbus can attempt to learn to tolerate the thin air of the region, spending weeks to even years circulating through climate controlled dorms until they reach one that is standard for the region. It's not possible for everyone to learn to acclimate, but plenty do try - after all, the party scene on Cumulus is legendary.