Vertical position
Vertical position or vertical location is a position along a vertical direction (the plumb line direction) above or below a given vertical datum (a reference level surface, such as mean sea level). Vertical distance or vertical separation is the distance between two vertical positions. Many vertical coordinates exist for expressing vertical position: depth, height, altitude, elevation, etc. Points lying on an equigeopotential surface are said to be on the same vertical level, as in a water level.
For the supply chain concept, see Vertical integration.Units[edit]
Vertical distance quantities, such as orthometric height, may be expressed in various units: metres, feet, etc.
Certain vertical coordinates are not based on length, for example, geopotential numbers have units of m2/s2.
Normalization by a constant nominal gravity value (units of m/s2) yields units of metre, as in geopotential height (based on standard gravity) or dynamic height (based on normal gravity at 45 degrees latitude). Despite the physical dimension and unit of length, the vertical coordinate does not represent distance in physical space, as would be measured with a ruler or tape measure.
Sometimes a geopotential metre (symbol gpm or m') or dynamic metre is introduced for emphasis.[3][4] However, this practice is not acceptable with the International System of Units (SI).[a]
Another non-SI unit is the vertical metre, introduced when there may be confusion between vertical, horizontal, or slant distances.
It is used for distance climbed during sports such as mountaineering, skiing, hiking, running or cycling[6]
In German-speaking countries the abbreviation 'Hm' for Höhenmeter ("height metre") is used; if it is preceded by a '±' it refers to the cumulative elevation gain.
Various instruments and techniques may be used for measuring vertical position:
Many physical phenomena are related to vertical position, as driven by gravity:
