The eponymous Silk Sky in the Valley is a multi-leveled, mostly-opaque structure made of the silk of domesticated cloud spiders (“Pocalo” literally means “spider web”). So how does light get down to the interior of the lower levels? The answer: LIGHT HOLES.
Throughout each province you’ll find numerous holes in the floor and in the ceiling, which allow sunlight and rainwater to filter through. Not too surprisingly, the further down you go, the less light and rainwater you get.
In general, for the lower provinces, populations cluster at the edges where the light is present throughout the day. An interior area that gets particularly good daylight coverage is called an oasis, and may have sufficient resources to support a small settlement or a waystation. Even if they aren’t suitable for permanent habitation, they’re usually an excellent source of rare plants, or can make for decent temporary campgrounds.