Vertical position or vertical location, also known as vertical level or simply level, is a position along a

vertical direction In astronomy, geography, and related sciences and contexts, a '' direction'' or '' plane'' passing by a given point is said to be vertical if it contains the local gravity direction at that point. Conversely, a direction or plane is said to be h ...

above or below a given

vertical datum In geodesy, surveying, hydrography and navigation, vertical datum or altimetric datum, is a reference coordinate surface used for vertical positions, such as the elevations of Earth-bound features (terrain, bathymetry, water level, and built str ...

(reference level). Vertical distance or vertical separation is the

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

between two vertical positions. Many vertical coordinates exist for expressing vertical position: depth, height, altitude, elevation, etc.

Definitions

The

International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...

(ISO), more specifically

ISO 19111 ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Iso ...

, offers the following two definitions: * ''depth'': "distance of a point from a chosen reference surface measured downward along a line perpendicular to that surface." * ''height'': "distance of a point from a chosen reference surface measured upward along a line perpendicular to that surface"; ISO 6709 (2008 version) makes the following additional definition: * ''

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

'': "height where the chosen reference surface is mean sea level" The

International Civil Aviation Organization The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...

(ICAO) offers similar definitions: Note: Annex 4 is one of the (currently) 19 annexes to the Chicago Convention on International Civil Aviation
ICAO Doc. 7300
. * ''

'': "the vertical distance of a level, a point or an object considered as a point, measured from the mean sea level (MSL);" *''height'': "the vertical distance of a level, a point or an object considered as a point, measured from a specific datum." ICAO further defines: * ''

elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Ver ...

': "the vertical distance of a point or a level, on or affixed to the surface of the earth, measured from mean sea level." I.e., elevation would be the altitude of the ground or a building.

Derived quantities

Several

physical quantities A physical quantity is a physical property of a material or system that can be quantified by measurement. A physical quantity can be expressed as a ''value'', which is the algebraic multiplication of a ' Numerical value ' and a ' Unit '. For exam ...

may be defined based on the definitions above: *

Depth below seafloor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most ...

* Depth in a well *

Drying height On a nautical chart, the drying height is the vertical distance of the seabed that is exposed by the tide, above the sea water level at the lowest astronomical tide A chart datum is the water level surface serving as origin of depths displaye ...

Dynamic height Dynamic height is a way of specifying the vertical position of a point above a vertical datum; it is an alternative for orthometric height or normal height. It can be computed dividing the location's geopotential number by the normal gravity at 4 ...

Ellipsoidal height Geodetic coordinates are a type of curvilinear orthogonal coordinate system used in geodesy based on a ''reference ellipsoid''. They include geodetic latitude (north/south) , ''longitude'' (east/west) , and ellipsoidal height (also known as geod ...

Geocentric altitude In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded description of the Universe with Earth at the center. Under most geocentric models, the Sun, Moon, stars, and ...

Geopotential Geopotential is the potential of the Earth's gravity field. For convenience it is often defined as the ''negative'' of the potential energy per unit mass, so that the gravity vector is obtained as the gradient of this potential, without the negat ...

* Heights in geodesy *

Height above mean sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as '' orthometric heights''. The c ...

Height above average terrain Height above average terrain (HAAT), or (less popularly) effective height above average terrain (EHAAT), is the vertical position of an antenna site is above the surrounding landscape. HAAT is used extensively in FM radio and television, as it i ...

Height above ground level In aviation, atmospheric sciences and broadcasting, a height above ground level (AGL or HAGL) is a height measured with respect to the underlying ground surface. This is as opposed to height above mean sea level (AMSL or HAMSL), height above ell ...

Measured depth In the oil industry measured depth (commonly referred to as MD, or just the depth) is the length of the drilled borehole. In conventional vertical wells, this coincides with the true vertical depth, but in directional or horizontal wells, espec ...

Normal height Normal heights is a type of height above sea level introduced by Mikhail Molodenskii. The normal height H^* (or H^N) of a point is computed as the ratio of a point's geopotential number (i.e. its geopotential difference with that of sea level), by t ...

Orthometric height The orthometric height is the vertical distance ''H'' along the plumb line from a point of interest to a reference surface known as the ''geoid'', the vertical datum that approximates mean sea level. Orthometric height is one of the scientific fo ...

Thickness (geology) Thickness in geology and mining refers to the distance across a packet of rock, whether it be a facies, stratum, bed, seam, lode etc. Thickness is measured at right angles to the surface of the seam or bed and thus independently of its spatial ...

True vertical depth True vertical depth'is the measurement of a straight line perpendicularly downwards from a horizontal plane. In the petroleum industry, true vertical depth, abbreviated as TVD, is the measurement from the surface to the bottom of the borehole ...

Units

Vertical distance quantities, such as

orthometric height The orthometric height is the vertical distance ''H'' along the plumb line from a point of interest to a reference surface known as the ''geoid'', the vertical datum that approximates mean sea level. Orthometric height is one of the scientific fo ...

, may be expressed in various units:

metres The metre (British spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most notable va ...

feet The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...

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

geopotential number Geopotential is the potential of the Earth's gravity field. For convenience it is often defined as the ''negative'' of the potential energy per unit mass, so that the gravity vector is obtained as the gradient of this potential, without the nega ...

s have units of m²/s². Normalization by a constant nominal gravity value (units of m/s²) yields units of metre, as in

geopotential height Geopotential height or geopotential altitude is a vertical coordinate referenced to Earth's mean sea level, an adjustment to geometric height (altitude above mean sea level) that accounts for the variation of gravity with latitude and altitude. Thu ...

(based on standard gravity) or

dynamic height Dynamic height is a way of specifying the vertical position of a point above a vertical datum; it is an alternative for orthometric height or normal height. It can be computed dividing the location's geopotential number by the normal gravity at 4 ...

(based on

normal gravity In geodesy and geophysics, theoretical gravity or normal gravity is an approximation of the true gravity on Earth's surface by means of a mathematical model representing Earth. The most common model of a smoothed Earth is a rotating Earth ellipsoi ...

at 45 degrees latitude). Despite the dimension, the vertical coordinate still does not represent distance, as would be measured with a ruler. Sometimes a standard ''geopotential metre'' (symbol gpm or m') is introduced for emphasis. However, this practice is not acceptable with the International System of Units (SI): the Guide for the Use of the International System of Units, section 7.5 (Unacceptability of mixing information with units), states that ''"When one gives the value of a quantity, any information concerning the quantity or its conditions of measurement must be presented in such a way as not to be associated with the unit."''. Another non-SI unit is the ''vertical metre'', introduced when there may be confusion between vertical, horizontal, or

slant distance In radio electronics, especially radar terminology, slant range or slant distance is the distance along the relative direction between two points. If the two points are at the same level (relative to a specific datum), the slant distance equals ...

s. It is used for distance climbed during sports such as mountaineering,

skiing Skiing is the use of skis to glide on snow. Variations of purpose include basic transport, a recreational activity, or a competitive winter sport. Many types of competitive skiing events are recognized by the International Olympic Committee ( ...

hiking Hiking is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century.AMATO, JOSEPH A. "Mind over Foot: Romantic Walking and Rambling." In ''On Foot: A Histor ...

running Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground (though there are exceptions). This is ...

cycling Cycling, also, when on a two-wheeled bicycle, called bicycling or biking, is the use of cycles for transport, recreation, exercise or sport. People engaged in cycling are referred to as "cyclists", "bicyclists", or "bikers". Apart from t ...

Nash, Mike, ''Exploring Prince George: A Guide to North Central B. C. Outdoors'', Vancouver: Rocky Mountain Books, 2004, p. 105. 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 In running, cycling, and mountaineering, cumulative elevation gain refers to the sum of every gain in elevation throughout an entire trip. It is sometimes also known as cumulative gain or elevation gain, or often in the context of mountain travel, ...

Measurement

Various instruments and techniques may be used for measuring vertical position: *

Altimeter An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth under water. The m ...

Bathymetry Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water ...

Benchmark (surveying) The term benchmark, bench mark, or survey benchmark originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle-iron could be placed to form a "bench" for a leveling rod, thus ensuring that a lev ...

Depth gauge A depth gauge is an instrument for measuring depth below a reference surface. They include depth gauges for underwater diving and similar applications, and engineering instruments used to measure the depth of holes and indentations from a refer ...

* Depth sounding *

Hypsometer A hypsometer is an instrument for measuring height or elevation. Two different principles may be used: trigonometry and atmospheric pressure. Etymology The English word ''hypsometer'' originates from the Ancient Greek words ὕψος (húpsos, ...

Topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sc ...

Tide gauge A tide gauge is a device for measuring the change in sea level relative to a vertical datum. It its also known as mareograph, marigraph, sea-level recorder and limnimeter. When applied to freshwater continental water bodies, the instrument ma ...

Water level (device) A water level ( el, Aλφαδολάστιχο or (υδροστάθμη) '' lfadolasticho') is a siphon utilizing two or more parts of the liquid water surface to establish a local horizontal line or plane of reference. It is used to determine ...

Phenomena

Many physical phenomena are related to vertical position, as driven by

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

: * Hydraulic head ** Stage (hydrology) *

Isostasy Isostasy (Greek ''ísos'' "equal", ''stásis'' "standstill") or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust (or lithosphere) and mantle such that the crust "floats" at an elevation that depends on its ...

Mean sea level There are several kinds of mean in mathematics, especially in statistics. Each mean serves to summarize a given group of data, often to better understand the overall value (magnitude and sign) of a given data set. For a data set, the '' ari ...

Geoid The geoid () is the shape that the ocean surface would take under the influence of the gravity of Earth, including gravitational attraction and Earth's rotation, if other influences such as winds and tides were absent. This surface is extended ...

Sea surface height Ocean surface topography or sea surface topography, also called ocean dynamic topography, are highs and lows on the ocean surface, similar to the hills and valleys of Earth's land surface depicted on a topographic map. These variations are ex ...

* Temperature lapse rate *

Terrain Terrain or relief (also topographical relief) involves the vertical and horizontal dimensions of land surface. The term bathymetry is used to describe underwater relief, while hypsometry studies terrain relative to sea level. The Latin wo ...

Digital terrain model A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, moon, or asteroid. A "global DEM" refers to a discrete g ...

Topographic prominence In topography, prominence (also referred to as autonomous height, relative height, and shoulder drop in US English, and drop or relative height in British English) measures the height of a mountain or hill's summit relative to the lowest contou ...

Vertical displacement In tectonics, vertical displacement refers to the shifting of land in a vertical direction, resulting in uplift and subsidence. The displacement of rock layers can provide information on how and why Earth's lithosphere changes throughout geolog ...

Post-glacial rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound ...

** Subsidence **

Tectonic uplift Tectonic uplift is the geologic uplift of Earth's surface that is attributed to plate tectonics. While isostatic response is important, an increase in the mean elevation of a region can only occur in response to tectonic processes of crustal th ...

Vertical pressure variation Vertical pressure variation is the variation in pressure as a function of elevation. Depending on the fluid in question and the context being referred to, it may also vary significantly in dimensions perpendicular to elevation as well, and these var ...

References

External links

*{{Commons category-inline Vertical position,