Top and bottom are opposite to each other relative location information. You usually take with respect to the gravity of the earth and the physical location orientation of people in this gravitational field. Below designated sites which are located in the effective direction of gravity. Above are places in the direction opposite to gravity.
Construed as equivalent directions, above and below the plane passing through a given location plumb ( vertical). Due to the spherical shape of the Earth 's gravity field, the perpendicular lines are not parallel to each other; therefore, each place has its own vertical. For people on the opposite side of the earth, the directions are up and down even reversed completely. Since the Earth also rotates and is not a perfect sphere, has the perpendicular direction generally not exactly at the center of the earth. In Geozentrum itself, there is no "down" more and each direction is "up ". Even in a state of free fall, for example, in a parabolic flight or on board the ISS, there is gravity and there is within this system is not up and down.
Objects can also regardless of their actual location have a top and bottom, resulting from the design or application. For example, the opening of a bottle with its upper end always, even when the bottle is located on a flat surface, and both ends are at the same level. The reason is that it was designed to, with its lower part ( ' ground' ) stand on a flat surface stable without losing its contents, even if the opening is not closed.
Also, documents, drawings and other such things is awarded a top and bottom. This applies even if they lie flat on a table. When the blade is in the correct direction, below is the side that is closest to the viewer; above the viewer farthest side.
The terminology is also applied to the social structure, in the sense of an upper and a lower layer, are consulted as a classification criterion values such as income, education, ethnicity or character.
In geography there is the universal convention that maps on the north side and the south side of the top is down. An exception to this are some historical maps. For cards that depict the north or south pole area centrally, a north orientation is not possible. Here the prime meridian on Arctic maps down to Antarctica map is often, however, oriented upward.
Rivers have an upper and a lower course.
In neighboring towns with names like Oberammergau (837 m above sea level. NN ) and Unterammergau ( 836 m above sea level. NN ) are also usually the name of that place is higher and which located deeper.