Landscape horizon
The boundary line between the sky and the visible surface of the earth is called the landscape horizon or horizon of a location on earth . It differs from the mathematical horizon - the horizontal plane in the position of the observer - in that the view is restricted by the natural landscape or by buildings in the area.
Impression of the landscape
The landscape horizon shapes the impression one has of one's surroundings and is z. B. an important motif-forming element in photography . It generally rises a few degrees above the mathematical horizon:
- at locations on the level by a few tenths of a degree to about 1 °,
- in the hill country and low mountain range by about 2 to 5 °,
- in the high mountains by 10 to about 45 °, so that large parts of the sky are already covered.
- Due to the curvature of the earth , it can only be below the mathematical horizon on high mountain peaks , as well as on the open sea (see chimney line ).
Observational Astronomy
For observational astronomy , the landscape horizon is important in several ways because it covers part of the starry sky . So he shortens
- the visibility of the stars, so
- their day curve and especially the duration of sunshine at the respective location.
- In the northern hemisphere , all rise and fall points move towards the south, but in the south of the earth towards the north.
The fact that weather and observatories are often located on mountain peaks is not only due to the deep landscape horizon and its wide view of the sky and the weather processes. Because with round summit shapes , the air currents are more laminar , so they generate less air turbulence and better seeing . In the mountains there is also less air and light pollution and therefore visibility is better.
For a location near a city, however, a high landscape horizon can be advantageous if it partially covers the skylight dome of a large city.