Understanding the Procedural Skybox

I am attempting to understand the Procedural Skybox that comes with Unity and I have so far drawn a blank on any resources explaining what it does, and how it does it. Specifically I am having trouble understanding which global variables Unity is passing to it in regards to the location of the sun and the main camera.

I'd like to understand these things so I can figure out how to give the horizon some curvature to it for high altitude flight. As well as remove the horizon and ground entirely for spaceflight, allowing me to do a seamless transition from space to the ground using the strength of procedural shaders.