Above mean sea level facts for kids
Above Mean Sea Level (often shortened to AMSL) is a way to measure how high something is. It tells you the elevation or altitude of a place compared to the average level of the ocean.
Engineers use AMSL to figure out how far a radio station's signal can reach. Pilots also use it a lot, as most heights for planes are measured and reported using AMSL. Scientists who study the Earth's atmosphere also use this measurement.
What is Above Mean Sea Level?
Imagine the ocean's surface. It's not perfectly flat! The sea moves up and down because of tides, wind, and even changes in air pressure. This means it's tricky to find one exact "sea level" for the whole planet.
So, when we talk about "mean sea level," we are talking about an average. It's like finding the middle point of all the ocean's ups and downs over a long time in a specific spot. This average level then becomes a starting point, or a "zero" line, for measuring height.
Why Do We Need It?
Using AMSL helps everyone agree on a standard way to measure height.
- For example, if a mountain is 1,000 meters AMSL, it means it's 1,000 meters higher than the average ocean surface.
- This is very important for things like building tall structures, creating accurate maps, or guiding airplanes safely.
How Do We Measure It?
Since the ocean isn't flat everywhere, different ways are used to figure out the "mean sea level":
- Local Measurements: Sometimes, people pick a specific spot on the coast and measure the sea level there for many years. They then calculate the average. This average becomes the "zero" point for maps and measurements in that area. For example, in Great Britain, maps use a measurement taken at Newlyn, Cornwall, between 1915 and 1921.
- Satellite Measurements: Modern systems like GPS use satellites to measure height. These systems don't rely on the actual ocean surface. Instead, they use a smooth, imaginary shape of the Earth called an ellipsoid. This gives a more global and consistent way to measure height, which is very useful for things like airplanes flying all over the world.
See also
In Spanish: Altura sobre el nivel del mar para niños
