Elevation




Height of a geographic location above a fixed reference point

For other uses, see Elevation (disambiguation).



Sign at 8,000 feet (2,438 m) in the San Bernardino Mountains of southern California (2009)





Contents






  • 1 Maps and GIS


  • 2 Global 1-kilometer map


  • 3 Hypsography


  • 4 Temperature


  • 5 See also


  • 6 References


  • 7 External links






Vertical distance comparison




Elevation histogram of the Earth's surface, of which approximately 71% is covered with water


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 § 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 is not to be confused with the distance from the center of the Earth. Due to the equatorial bulge, the summits of Mount Everest and Chimborazo have, respectively, the largest elevation and the largest geocentric distance.



Maps and GIS




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





Landsat Image over SRTM Elevation by NASA, showing the Cape Peninsula and Cape of Good Hope, 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 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


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.

























































































N60-90, W150-180
N60-90, W120-150
N60-90, W90-120
N60-90, W60-90
N60-90, W30-60
N60-90, W0-30
N60-90, E0-30
N60-90, E30-60
N60-90, E60-90
N60-90, E90-120
N60-90, E120-150
N60-90, E150-180

N30-60, W150-180
N30-60, W120-150
N30-60, W90-120
N30-60, W60-90
N30-60, W30-60
N30-60, W0-30
N30-60, E0-30
N30-60, E30-60
N30-60, E60-90
N30-60, E90-120
N30-60, E120-150
N30-60, E150-180

N0-30, W150-180
N0-30, W120-150
N0-30, W90-120
N0-30, W60-90
N0-30, W30-60
N0-60, W0-30
N0-60, E0-30
N0-60, E30-60
N0-60, E60-90
N0-60, E90-120
N0-60, E120-150
N0-60, E150-180

S0-30, W150-180
S0-30, W120-150
S0-30, W90-120
S0-30, W60-90
S0-30, W30-60
S0-30, W0-30
S0-30, E0-30
S0-30, E30-60
S0-30, E60-90
S0-30, E90-120
S0-30, E120-150
S0-30, E150-180

S30-60, W150
S30-60, W120
S30-60, W90-120
S30-60, W60-90
S30-60, W30-60
S30-60, W0-30
S30-60, E0-30
S30-60, E30-60
S30-60, E60-90
S30-60, E90-120
S30-60, E120-150
S30-60, E150-180

S60-90, W150-180
S60-90, W120-150
S60-90, W90-120
S60-90, W60-90
S60-90, W30-60
S60-90, W0-30
S60-90, E0-30
S60-90, E30-60
S60-90, E60-90
S60-90, E90-120
S60-90, E120-150
S60-90, E150-180
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






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 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 which is taken relative to the sea level.




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



Temperature


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



See also




  • Height
    • Orthometric height



  • Geodesy

    • Geodesy of North America


      • Sea Level Datum of 1929 later National Geodetic Vertical Datum of 1929 (NGVD 29)


      • 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





  1. ^ Survey, U.S. Geological. "The National Map: Elevation". nationalmap.gov. Retrieved 2017-02-24..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}


  2. ^ Quantifying Elevation and Temperature




External links








  • U.S. National Geodetic Survey website

    • Geodetic Glossary @ NGS

    • NGVD 29 to 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 elevation of any place




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