The elevation of a geographic location is its height above a fixed reference point, often the mean sea level. Elevation, or geometric height, 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.

Less commonly, elevation is measured using the center of the Earth as the reference point. Due to equatorial bulge, there is debate which of the summits of Mt. Everest or Chimborazo is at the higher elevation, as the Chimborazo summit is further from the Earth's center while the Mt. Everest summit is higher above mean sea level.

Maps and GIS

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.

To determine elevation of a place, it must be surveyed, in reference to a ground control point.

Topography

The elevation of a mountain usually refers to its summit. The elevation of a hill also refers to the summit. A valley's elevation is usually taken from the lowest point but is often taken all over the valley.

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.

See also

• altitude
• 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)
• Highest mountain peaks of North America
• List of highest mountains
• List of highest towns by country
• physical geography
• summit (topography)
• topographic isolation
• topographic map
• topographic prominence
• topography

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)
• bivouac.com Canadian Mountain Encyclopedia
• peakbagger.com
• peaklist.org
• peakware.com World Mountain Encyclopedia
• summitpost.org