Elevation
Height above a reference geoid, distinct from altitude and depth.
Elevation is a measurement of the height of a point on the Earth's surface above or below a fixed reference point, most commonly a reference geoid, which is a mathematical model of the Earth's sea level as an equipotential gravitational surface. The term is primarily used for points on the Earth's surface, while altitude or geopotential height is used for points above the surface, and depth for points below.
- field
- Geography, Aviation, Geodesy
- known_for
- Measurement of height above a reference geoid; distinction from altitude and depth; use in topographic maps and GIS
- related_terms
- Altitude, Geopotential height, Depth, Geocentric distance
- key_organizations
- ICAO, USGS
- notable_examples
- Mount Everest (largest elevation), Chimborazo (largest geocentric distance)
Lore & Background
Elevation is defined as the height of a geographic location above or below a fixed reference point, most commonly a reference geoid—a mathematical model of Earth's sea level as an equipotential gravitational surface. It is not to be confused with the distance from the center of the Earth; due to the equatorial bulge, Mount Everest has the largest elevation, while Chimborazo has the largest geocentric distance. In aviation, the ICAO defines elevation or aerodrome elevation as the highest point of the landing area, often measured in feet and found in approach charts.
Reader's Guide
Elevation is a fundamental concept in geography, aviation, and geodesy, serving as the basis for topographic maps and digital elevation models (DEMs). In a Geographic Information System (GIS), DEMs represent surface topography through raster datasets, while digital terrain models offer another representation. The USGS is developing a 3D Elevation Program (3DEP) to meet growing needs for high-quality topographic data, using LiDAR data over the conterminous United States, Hawaii, and U.S. territories, with three bare earth DEM layers at resolutions of 1/3, 1, and 2 arcseconds.
Did You Know?
- Elevation is not to be confused with the distance from the center of the Earth; Mount Everest has the largest elevation, while Chimborazo has the largest geocentric distance.
- In aviation, the ICAO defines aerodrome elevation as the highest point of the landing area.
- The USGS 3D Elevation Program (3DEP) provides three bare earth DEM layers at resolutions of 1/3, 1, and 2 arcseconds.
- A topographical map is the main type of map used to depict elevation, often through contour lines.
Frequently Asked Questions
What is Elevation in geography?
Elevation describes how far a point on Earth's surface sits above or below a standardized reference level, typically the geoid. It is the standard term used on topographic maps and in GIS to express the vertical position of land features.
How does Elevation differ from Altitude and Depth?
Elevation applies specifically to points on the Earth's surface, whereas altitude (or geopotential height) describes objects above the surface such as aircraft, and depth measures how far below the surface something lies. Keeping these three terms separate prevents confusion across geography, aviation, and oceanography.
What is the geoid and why is it the reference for Elevation?
The geoid is a mathematical model of Earth's sea level defined as an equipotential gravitational surface, and it serves as the baseline from which elevation is measured. Without this shared reference, comparing heights between different locations would lack consistency.
What are some notable Elevation examples?
Mount Everest holds the record for the greatest elevation above sea level, while Chimborazo in Ecuador actually sits farthest from Earth's center because of the planet's equatorial bulge. These two peaks show that the 'highest' point depends on whether you measure elevation or geocentric distance.
Which organizations set standards for Elevation measurement?
The ICAO governs height-related standards in aviation, while the USGS produces the topographic data where elevation figures appear for the general public. Together they ensure that elevation values are reported consistently in their respective fields.
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