Elevation

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. This helps us understand how high or low a place is compared to the average level of the oceans.

We usually talk about elevation when we refer to points on the Earth's surface, like mountains or valleys. For things above the surface, such as an aircraft in flight or a spacecraft in orbit, we use terms like altitude or geopotential height. For points below the surface, we use the word depth.

Elevation is different from the distance from the center of the Earth. Because the Earth is not a perfect sphere—it bulges slightly at the equator—some mountains have both high elevation and a large distance from the Earth's center. For example, the summits of Mount Everest and Chimborazo are special in these ways.

Aviation

In aviation, the term elevation or aerodrome elevation means the highest point of a landing area. It is usually measured in feet and can be seen on charts that help planes land safely. This is different from terms like altitude or height.

Maps and GIS

A geographic information system is a special kind of computer system that helps us see, change, collect, and store information about places and what is on or near those places. It helps us understand patterns and relationships in the land better. The tools in a GIS let us work with the data to study places or make maps.

A topographical map is a map that shows how high or low different parts of the land are, often using special lines called contour lines. In a GIS, we can use something called digital elevation models, or DEMs, to show the shape of the land. These are made using a raster, which is like a grid, that has information about how high each spot is. Another way to show land shapes in GIS is with digital terrain models.

The United States Geologic Survey is working on a project called the 3D Elevation Program (3DEP). This program collects very detailed information about how high places are in the United States, including Hawaii and other U.S. areas, using a special kind of aerial scanning called LiDAR. The 3DEP includes three sets of data that show the height of the land very clearly.