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The Info List - Elevation


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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 ). 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, 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

Part of a topographic map of Haleakala
Haleakala
( Hawaii
Hawaii
), showing elevation. Landsat
Landsat
Image over SRTM
SRTM
Elevation
Elevation
by NASA
NASA
, showing the Cape Peninsula
Cape Peninsula
and Cape of Good Hope
Cape of Good Hope
, South Africa
South Africa
in the foreground.

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.

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.

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

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

HYPSOGRAPHY is the study of the distribution of elevations on the surface of the Earth
Earth
, although the term is sometimes also applied to other rocky planets such as Mars
Mars
or Venus
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

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

SEE ALSO

* Height
Height

* Orthometric height

* Geodesy
Geodesy

* Geodesy
Geodesy
of North America
North America

* Sea Level Datum of 1929 later National Geodetic Vertical Datum of 1929 ( NGVD 29
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
Normalhöhennull
* Physical geography * Table of the highest major summits of North America
North America
* Topographic isolation
Topographic isolation
* Topographic prominence
Topographic prominence
* Topography
Topography
* Vertical pressure variation

REFERENCES

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

.