Observations/Perspective/en

Perspective

The appearance to the eye of objects in respect to their relative distance and positions, for example the way that objects appear smaller when they are farther away and the way parallel lines appear to meet each other at a point in the distance (Vanishing point).

Vanishing point

The vanishing point is the point in the distance where parallel lines seem to meet, due to perspective. We know that trains tracks don't actually get narrower they further they go because the train would derail. This narrowing / vanishing effect is due to perspective and the way our eyes work.

Crepuscular Rays

Crepuscular rays occur when objects such as mountain peaks or clouds partially shadow the sun's rays. The name crepuscular means "relating to twilight" and these rays are observed at sunrise and sunset. Crepuscular rays appear to diverge outward from the setting sun, and are visible only when the atmosphere contains enough haze or dust particles so that sunlight in unshadowed areas can be scattered toward the observer.

Anticrepuscular Rays

Have you ever witnessed rays of sunlight seemingly converging in the opposite direction of the setting sun? These fascinating rays, known as anticrepuscular rays, create a mesmerizing display in the sky. While crepuscular rays appear to converge on the sun itself, anticrepuscular rays appear to converge towards the antisolar point, which is directly opposite the sun in the sky.

To observe anticrepuscular rays, you must position yourself with your back to the sun or sunset point. As you gaze towards the horizon opposite the sun, you may be fortunate enough to witness these parallel shafts of sunlight streaming through gaps in the clouds. The seemingly peculiar directions of these rays are actually a result of perspective. Just like a straight road appears to converge towards the horizon, anticrepuscular rays appear to converge towards the opposite horizon.

While anticrepuscular rays are not necessarily rare, they do require careful observation. When you notice crepuscular rays illuminating the sky, it's time to turn around and search for their opposite counterparts. By shifting your focus away from the sun, you may be rewarded with the breathtaking sight of anticrepuscular rays stretching across the sky.

Azimuthal grid of vision

If you took all these facts on how perspective works and apply it to every direction you can look, apply the same rule of perspectve to all the directions you can see. You might not see parallel lines in the sky, but the same rule of perspective applies. The net effect of your "personal perspective" in all directions result is called a "dome of vision", "arc of the horizon", or an "Azemuthal grid of vision".

It is important to realize this "dome of vision" is not the firmament or a dome over earth, it is an invisible region of the limitations of how far we can see in any given direction.