I managed to get through the section on the horizon line, and, while I agree with your synopsis, have to disagree with a number of details. I'll address the rest later when I have time.
The Horizon Line:
Apparently the Horizon at sea-level, for an observer with a height of 1.70m standing on the ground, is 4.65 km. It rests at ones relaxed eye level.
While the horizon does rest at eye level, it does not represent the limit of one's vision. The furthest distance visible is dependant on the size of the object visible. If the size and distance of an object mathematically result in the angular size of the object being less than one arc second, the physical shape of that object will become indiscernable to the naked eye.
If one is to hold their gaze to the highest angle they can, whilst standing straight without tilting their head, the highest point in which they can see is actually further than 4.65km. This fact has lead many to assume that this means that the horizon is the distance in which things begin to drop behind the curvature of the earth, when actually natural eyesight has an uneven threshold to which it is limited and the Horizon line - the medium band of this threshold has the closest retention. This is because the eyes lenses are receptive not projective and the pupil is the part of the organ which absorbs/attracts the light into the rods and cones which then filter the optical data such as colour depth etc. that the brain then creates a 3D image of.
It is correct that the eyes lenses do not recieve the light, but merely refract the light rays from a common point source onto a focal point on the retina, which recieves and sends colour information, and two-dimensional information only. Depth is interpreted from having two vantage points (eyes) and using the parallax between them to judge depth. There is nothing about the optical properties of the eyes that causes them to have different limits of vision due at different inclinations. The eye's lens and retina have the same shape when it's angled 45 degrees up as when it's level, and therefore the same refractive and receptive properties at both angles, and therefore there is no change in perspective when you look at the sky.
However the visual threshold is limited to different distances depending on the level of the atmosphere it is receiving from. Variables in the saturation of light and its angle/arc-velocity, moisture and air pressure (which create distortions/accentuations or diminishment of the actual size and or distance to which sense data can be received), are what determines the limit of ones visual scope at any given angle.
this is correct as far as I can tell
The horizon line is the area of ones visual threshold which is limited the most,
Because:
1. light has travelled the furthest to get there.
2. The arc-velocity (otherwise known as bendy-light) is at the greatest compression thus acting as a filter on the retention rate of visual reception.
3.The atmosphere is at its most dense serving as a further filter.
4. Additionally as potential weather variables:
Natural lens-like refraction (the effect of an image projecting closer or further away than it is) and further velocity of arcing – resulting in the appearance being compressed so to appear smaller due to moisture and or ice crystals at low altitude, this being dependant on the weather and/or season.
All of these variables account for a number of potential combinations of reasons for why an object may appear further away or closer than it is in reality.
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The reverse of what has been explained here can account for why the limit of one's scope is extended further as the angle of gaze is elevated above the horizon.[/size][/font]
I'm not sure that anything should appear closer or further away than in reality, so I see no reason to address your reasoning to support this phenomenon.
I should point out that there are two horizons. This is very important when discussing perspective. There is the visible horizon, that is the apparent line the divides sea from sky, and there is the true, mathematical horizon, which represents a direction that is truely horizontal from eye/camera level. This distinction is important because the visible horizon would be subject to all of the phenomena you have just listed, plus the curvature of a concave earth, and can therefore deviate from the true mathematical perspective, and become either below or above truely horizontal. But due to all of these same phenomena, the actual distance of the visible horizon can vary greatly. In the context of a round earth, the actual edge of the earth is the limit, give or take a few kms due to refraction. For a flat earth, same thing in the context of bendy light, and without bendy light, the horizon represents whatever distance becomes less than 1 arc second from the edge of the spotlight sun. So, your conclusion here, I guess, is technically correct, but my point is that there is no actual fixed visual threshold.
I apologise if I misinterpreted the gist of your message, I feel like I'm not actually arguing your points precisely. I struggle greatly with my communication skills, and your vocabulary and syntax are more formal than I'm used to. I remain confident in my powers of spatial reasoning, however, and hope I have communicated the conclusions I've made with my strengths well enough for you to understand them, even if they don't adress your points precisely.