Besides, the vista reflects more light, which results in more image-forming information (reflected photons from the vista) reaching the human eye. When the Sun shines higher, less amount of light is scattered by the atmosphere towards the observer. The solar azimuth always goes along with its angle above the horizon. It also reflects changes the contrast of this object. On the other hand, the Sun travels across the sky changing its position against the observed object. 1, 2 – represents a moment after sunrise 3, 4 – a vista around noon, when the angular distance to the Sun is the biggest, hence visibility is the best (Malm, 2016). The effect of progressively shifting Sun angle on the appearance of a vista as seen from Canyonlands National Park. The most important astronomical factors determining the conditions of long-distance observations are: There are only a few places on Earth, where the similar or bigger result can be achieved. Both mountain ranges separated by lowland from each other must be high enough to be visible at long range like this. The circumstances such that are the most favourable for seeing and capturing objects from the biggest possible distance, what the best example is the current world's record established between the Pyrenees and Alps in Europe. An opposite situation takes place, when the remote massive chains are separated by a vast plain, lowland, or large water body. It happens usually inside the massive, often parallel mountain range, where a lot of peaks having a similar altitude block some distant mountain chains visible in the theoretical sense. Sometimes the prominent object can be hidden by another one standing somewhere in the middle between him and the observer. The telecommunications transmitters are often inherent elements of the mountains, making them easy distinguishable from others. Likewise separated mountains, industrial telecoms, and infrastructure objects are also visible from range because they are usually higher than the surrounding area. The best visible are freestanding mountains or mountain ranges isolated from the mountain chain regardless of their relative altitude. The location of the observed object plays an important role, making it visible or not even from a small distance.

Unlike mountains, industrial and infrastructure objects are usually much thinner, what makes them hard to notice and photography because of their angular width. The same situation applies to the mountains more prominent than adjacent ones. It refers to these mountains, where some rock protrusions stand on the top. The objects, whose appearance is different from others are recognizable and detectable easier. Main aspects of long distance observations Topographic 6 Longest distance observations by country.1.4.4 Light reflection at angle of incidence.1.2.4 Changes the range of azimuth at moonrise and moonset.1.2.3 Seasonal variations of the sunrise and sunset azimuth.1.1.3 Topography along the line of sight.1 Main aspects of long distance observations.

Dark moonlight mountain top