# Vertical position

**Vertical position** or **vertical location** is a position along a vertical direction above or below a given vertical datum.
**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.
Each quantity may be expressed in various units: metres, feet, etc.

## Definitions

The International Organization for Standardization (ISO), more specifically ISO 19111, offers the following two definitions:[1]

*depth*: "distance of a point from a chosen reference surface measured downward along a line perpendicular to that surface."[1]*height*: "distance of a point from a chosen reference surface measured upward along a line perpendicular to that surface";[1]

ISO 6709 (2008 version) makes the following additional definition:

*altitude*: "height where the chosen reference surface is mean sea level"[1]

The International Civil Aviation Organization (ICAO) offers similar definitions:[2]

*altitude*: "the vertical distance of a level, a point or an object considered as a point, measured from the mean sea level (MSL);"[2]*height*: "the vertical distance of a level, a point or an object considered as a point, measured from an specific datum."[2]

ICAO further defines:

*elevation': "the vertical distance of a point or a level, on or affixed to the surface of the earth, measured from mean sea level."[2]*

I.e., elevation would be the altitude of the ground or a building.

Certain vertical coordinates are not based on length, for example, geopotential numbers.

## See also

- Altimeter
- Bathymetry
- Chart datum
- Depth below seafloor
- Depth gauge
- Depth sounding
- Depth in a well
- Digital elevation model
- Drying height
- Dynamic height
- Ellipsoidal height
- Geopotential
- Geographic coordinates
- Geoid
- Height above mean sea level
- Height above average terrain
- Height above ground level
- Horizontal position
- Hydraulic head
- Hypsometer
- Isostasy
- Mean sea level
- Measured depth
- Normal height
- Orthometric height
- Physical geodesy
- Post-glacial rebound
- Stage (hydrology)
- Sea surface height
- Subsidence
- Tectonic uplift
- Temperature lapse rate
- Thickness (geology)
- Tide gauge
- True vertical depth
- Vertical and horizontal
- Vertical pressure variation
- Vertical separation (aviation)
- Water level

## References

- "ISO 6709:2008(en) preview".
*www.iso.org*. ISO. Retrieved 8 June 2016. - United Nations - International Civil Aviation Organization. "Annex 4: Aeronautical Charts - Chapter 1 (Definitions, Applicability and Availbility)" (PDF). Archived from the original (PDF) on 2016-09-17. Note: Annex 4 is one of the (currently) 19 annexes to the Chicago Convention on International Civil Aviation (ICAO Doc. 7300).