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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 system, vertical datum). The term "elevation" is mainly used when referring to points on the Earth's surface, while "altitude" or "geopotential height" is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and "depth" is used for points below the surface. Elevation
Elevation
is not to be confused with the distance from the center of the Earth; due to equatorial bulge, the summits of Mt. Everest and Chimborazo have, respectively, the largest elevation and the largest geocentric distance. Maps and GIS[edit]

Part of a topographic map of Haleakala
Haleakala
(Hawaii), showing elevation.

Landsat
Landsat
Image over SRTM
SRTM
Elevation
Elevation
by NASA, showing the Cape Peninsula and Cape of Good Hope, South Africa
South Africa
in the foreground.[1]

GIS or geographic information system is a computer system that allows for visualizing, manipulating, capturing, and storage of data with associated attributes. GIS offers better understanding of patterns and relationships of the landscape at different scales. Tools inside the GIS allow for manipulation of data for spatial analysis or cartography.

Heightmap of Earth's surface (including water and ice) in equirectangular projection, normalized as 8-bit grayscale, where lighter values indicate higher elevation.

A topographical map is the main type of map used to depict elevation, often through use of contour lines. In a Geographic
Geographic
Information System (GIS), digital elevation models (DEM) are commonly used to represent the surface (topography) of a place, through a raster (grid) dataset of elevations. Digital terrain models are another way to represent terrain in GIS. USGS (United States Geologic Survey) is developing a 3D Elevation Program (3DEP) to keep up with growing needs for high quality topographic data. 3DEP is a collection of enhanced elevation data in the form of high quality LiDAR data over the conterminous United States, Hawaii, and the U.S. territories. There are three bare earth DEM layers in 3DEP which are nationally seamless at the resolution of 1/3, 1, and 2 arcseconds.[1] Global 1-kilometer map[edit] This map is derived from GTOPO30 data that describes the elevation of Earth's terrain at intervals of 30 arcseconds (approximately 1 km). It uses color and shading instead of contour lines to indicate elevation.

Each tile is available at a resolution of 1800 × 1800 pixels (approximate file size 1 MB, 60 pixels = 1 degree, 1 pixel = 1 minute)

Processed LiDAR point cloud showing not only elevation, but heights of features as well.

Hypsography[edit]

It has been suggested that this section be split out into another article titled Hypsography. (Discuss) (July 2014)

Hypsography
Hypsography
is the study of the distribution of elevations on the surface of the Earth, although the term is sometimes also applied to other rocky planets such as Mars
Mars
or Venus. The term originates from the Greek word ὕψος "hypsos" meaning height. Most often it is used only in reference to elevation of land but a complete description of Earth's solid surface requires a description of the seafloor as well. Related to the term hypsometry, the measurement of these elevations of a planet's solid surface are taken relative to mean datum, except for Earth
Earth
which is taken relative to the sea level.

Hypsography
Hypsography
of the Earth. Notice that Earth
Earth
has two peaks in elevation, one for the continents, the other for the ocean floors.

Temperature[edit] In the troposphere, temperatures decrease with altitude. This lapse rate is approximately 6.5 °C/km.[2] See also[edit]

Height

Orthometric height

Geodesy

Geodesy
Geodesy
of North America

Sea Level Datum of 1929
Sea Level Datum of 1929
later National Geodetic Vertical Datum of 1929 (NGVD 29) North American Vertical Datum of 1988
North American Vertical Datum of 1988
(NAVD 88)

List of European cities by elevation List of highest mountains List of highest towns by country Normaal Amsterdams Peil Normalhöhennull Physical geography Table of the highest major summits of North America Topographic isolation Topographic prominence Topography Vertical pressure variation

References[edit]

^ Survey, U.S. Geological. "The National Map: Elevation". nationalmap.gov. Retrieved 2017-02-24.  ^ Quantifying Elevation
Elevation
and Temperature

External links[edit]

Look up elevation in Wiktionary, the free dictionary.

U.S. National Geodetic Survey website

Geodetic Glossary @ NGS NGVD 29
NGVD 29
to NAVD 88
NAVD 88
online elevation converter @ NGS

United States Geological Survey website Geographical Survey Institute Downloadable ETOPO2 Raw Data Database (2 minute grid) Downloadable ETOPO5 Raw Data Database (5 minute grid) Find the elev

.