This would be insufficient and has been covered in other threads. As light goes through a thicker medium, its apparent size increases. Thus as the sun-spotlight recedes on the horizon, it must go through more atmodisc giving it the larger appearance (nearly the same size as the sun at noon) until it has receded to the point that it vanishes. A simple example of this effect is a streetlight during a clear night and the same streetlight on a foggy night. Alternately, city lights in a distance. They appear as one very large light from far away, but as you approach and there is less medium between you and the city, the lights shrink until they become visible as distinct points.
I think you meant as a
point light source goes through a
particulate medium its apparent size increases.
When you see streetlights in the fog, you aren't fooled that the lights have magically grown in size, you simply see the
"bloom" around the light. The sun and moon are a different story, since they aren't point light sources, they have what's called a
"visible disk." This means you can clearly see the line that forms the objects circumference. (Of course if it were so foggy that you couldn't see the clear circumference, then of course it's going to appear bigger.)
It's a well known optical illusion (meaning that it isn't real, just a trick of the eye) that objects at the horizon appear larger than they actually are, simply because we are putting them in the context of ground objects. When I was in college I assisted with an experiment which proved this. Eliminate the context cues, and a sun or moon on the horizion appears no larger than it does overhead. It has
nothing to do with through how much atmosphere the light must travel.