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Elevation

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Elevation is the vertical distance of a location from a fixed reference point. This reference point is most commonly a geoid. A geoid is a mathematical model of the Earth's sea level. It acts as an equipotential gravitational surface. This means it represents a surface where gravity is consistent.

vertical distances
vertical distances

Understanding elevation is vital for geography, aviation, and mapping. It allows us to define the height of land and the shape of our planet.

It is important to distinguish elevation from other vertical measurements. We use the term elevation for points on the Earth's surface. When discussing objects above the surface, such as aircraft or spacecraft, we use altitude. We also use the term geopotential height for these high-flying objects. For points located below the surface, the correct term is depth.

Earth elevation histogram 2
Earth elevation histogram 2

Using these specific terms ensures clarity in scientific and technical fields.

Elevation is not the same as the distance from the center of the Earth. This distinction exists because of the equatorial bulge. The Earth is not a perfect sphere. It bulges outward at the equator. Because of this shape, different peaks have different characteristics. Mount Everest has the largest elevation on Earth. However, the summit of Chimborazo has the largest geocentric distance. This means Chimborazo is further from the Earth's center than Everest is.

vertical distances
vertical distances

In the field of aviation, elevation has a very specific definition. The International Civil Aviation Organization, or ICAO, defines aerodrome elevation. This refers specifically to the highest point of a landing area. Pilots find this information in approach charts for an aerodrome. It is often measured in feet. Aviation professionals must not confuse aerodrome elevation with altitude or height.

vertical distances
vertical distances

Geographers use several tools to visualize and study the Earth's surface. Topographic maps are a primary tool for depicting elevation. These maps often use contour lines to show the shape of the land.

Topomapcropped
Topomapcropped

Another advanced tool is a Geographic Information System, or GIS. A GIS is a computer system used for capturing and storing data. It allows users to manipulate and visualize data with specific attributes. This helps scientists understand landscape patterns and relationships at different scales.

Within a GIS, researchers use digital elevation models, known as DEMs. A DEM represents the topography of a place using a raster dataset. A raster is a grid of elevation values. Digital terrain models are another method used to represent terrain in these systems.

srtm ramp2.world.21600x10800
srtm ramp2.world.21600x10800

These digital models allow for complex spatial analysis and cartography.

The United States Geological Survey, or USGS, is currently working on a major initiative. This is called the 3D Elevation Program, or 3DEP. The goal of 3DEP is to meet the growing need for high-quality topographic data. This program uses enhanced LiDAR data. LiDAR is a high-quality method for gathering elevation information.

Satellite image of Cape peninsula
Satellite image of Cape peninsula

This data covers the conterminous United States, Hawaii, and various U.S. territories.

The 3DEP project provides three specific bare earth DEM layers. These layers are designed to be nationally seamless. They are provided at resolutions of 1/3, 1, and 2 arcseconds. This high level of detail allows for very precise mapping. Such precision is essential for modern geographic studies and land management.

srtm ramp2.world.21600x10800
srtm ramp2.world.21600x10800

By using these layers, scientists can study the Earth's surface with incredible accuracy.

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🖼️ Images & Media (5)
File:vertical distances.svg
vertical distances.svg
File:Earth elevation histogram 2.svg
Earth elevation histogram 2.svg
File:Topomapcropped.jpg
Topomapcropped.jpg
File:Satellite image of Cape peninsula.jpg
Satellite image of Cape peninsula.jpg
File:srtm ramp2.world.21600x10800.jpg
srtm ramp2.world.21600x10800.jpg
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