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Geography 101: Find Your Elevation

Mount Everest with an elevation of 8,848 meters is Earth’s highest mountain above sea level

Ever taken a picture from the top of a mountain and wondered what number to put in the Instagram caption to tell the world how ‘high’ you are? The number you’re looking for is called elevation.

What is elevation?

Simply put, elevation is a geographical term used to describe the vertical distance between a predetermined reference point (like the mean sea level) and the top of an object (like a mountain). Commonly confused with altitude, the basic difference between the two is that while elevation refers to the distance from a fixed point on the Earth’s surface, altitude is used to measure the height of a point in space, such as an airplane or a skydiver.

How is elevation calculated?

In 2015, North America’s tallest mountain, Mount McKinley, got a new name: Denali. But that change did not come in solitary. The US Geological Survey announced that it was shaving 10 feet (3 meters) off Denali’s highest point to set its new elevation at 20,310 feet (6,200 meters).

Global Position System equipment being set up at Denali’s highest point for precise summit elevation data. Credit: Blaine Horner/CompassData

Formerly, elevation used to be calculated using mathematical formulas of trigonometry. The horizontal distance between the two points and the vertical angle measured between them would yield the elevation of the object. Denali’s earlier elevation, meanwhile, was determined by a more advanced method of taking aerial radar measurements. But clearly, even that technique was not sufficient.

Today, modern GPS techniques are used to determine the elevation of a place. Just like you need three satellites to ‘triangulate’ your precise position on Earth, adding a fourth one to the mix will give you the height of that location.

But, in reality, this is not as simple as it sounds. Even GPS receivers can give you varied elevation results based on the baseline they are referencing to. Since the Earth’s surface is not consistent, scientists have developed various theoretical models called ‘vertical datums’ to represent the shape of our planet. Here’s an article that gives a wonderful explanation of how different datums can give different elevation results.

How can I find my elevation?

By now, you may have become curious to find the elevation of your current location. Thankfully, you don’t have to do a crash course in elevation calculation to satiate that curiosity. There are a host of web tools available at your disposal for just that. Elevation Map, for example, uses data from LiDAR digital elevation models to give you an approximate elevation value of the desired location with a simple click:

For more professional use, Google Maps Platform has an Elevation API as part of its client-side Maps JavaScript API. This API not only provides elevation data for all locations on the surface of the earth, it also returns negative values if you search for depth locations on the ocean floor.

To sum up, elevation is the vertical distance between two points on the Earth’s surface. There are various vertical datums governing the measurement of elevation, and their understanding is important to use elevation effectively.

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