For a more complex understanding, you need to think about the light paths to the camera (or eye, same thing). Here’s a setup of six triangles at various distances. The top view is a side view showing the light paths. It’s greatly magnified vertically so you can see what is going on.
No refraction is used here.
The light blue line is the line of sight to the horizon. Notice that it just clips the last triangle #6, which you can just see peeking over the horizon. You can also see all of the first four triangles ... Read even more
No refraction is used here.
The light blue line is the line of sight to the horizon. Notice that it just clips the last triangle #6, which you can just see peeking over the horizon. You can also see all of the first four triangles ... Read even more