# Elevation: what is it and how to define it?

We all studied geography at school and are familiar with the term “height above sea level” firsthand. This definition can be found in popular science television programs, on the pages of magazines, newspapers and other media. Let’s look at modern ways to define it.

• What is the height above sea level
• 2How to know the height above sea level
• 3The highest and lowest land area above sea level.
• 4The dependence of pressure on height above sea level

## What is the height above sea level

The sea level, relative to which the distance to the object is measured, is a water surface at rest, perpendicular to the resultant forces applied to the mass of water. The water level changes very often and the fault of this phase of the moon, the strength of the sun and wind, evaporation. Therefore, to calculate the average value, it is necessary to carry out the necessary calculations for years.

The height above sea level is a point (coordinate) in a three-dimensional area, which indicates how high a certain object is in relation to the sea level taken as zero. It can also be tentatively defined as a vertical from the subject to the average height above sea level, without taking into account the ebb and flow. The height of a point located above the level is considered positive, below – negative. The other two coordinates of the geographical location of the object – longitude and latitude.

If we take Russia as an example, then its highest point is Elbrus – 5642 meters, and the lowest is the Caspian Sea, the highest point of which is approximately 28 meters.

## How to know the height above sea level

In the old manner, the height above sea level can be viewed in special topographic maps that show all heights. But there are more modern methods.

1. To find out what height above sea level, you can use a satellite navigator, working from a specific program, for example, Google or Google Earth. First you need to download one of the applications on your smartphone or computer and use the tips to determine the distance from the sea level to the object you need. Working with programs is very simple: move the cursor to the desired place on the map, and the information is given automatically.
2. Measurement of the level of a specific location is available on GPS devices. Instruments determine heights based on information received from satellites. GPS receivers with a built-in altimeter barometer have the highest accuracy.
3. In the search box of the Yandex browser, drive in “height above sea level” and the city, country, mountain, etc. you need. Especially this information will be useful for travelers who are going to conquer mountain peaks. So you will be able to know in advance which heights you will have to overcome and prepare for the ascent.
4. How to determine the height of the application knows called Altitude, installed on smartphones. It determines the point above sea level in real time, as well as the speed of movement and other data. The results may not be entirely accurate with a difference of one and a half to two divisions.

Also, measurements of the height of the terrain above sea level can be performed using an altimeter – a tool that is used to measure elevation heights or a point above sea level. Using an altimeter is very simple:

• start the device and determine the value of blood pressure corresponding to the current weather conditions;
• Calibrate the instrument and hold down the “Set” button. After that, the device will automatically switch to the desired mode and indicate the altitude pressure at the current time;
• reduce the values ​​to normal using the “Set” button. Having saved the received parameters in the main menu, the height above the sea level of the desired object will be displayed on the screen.

How to find out the height above sea level using one or another method is a purely individual matter, but the altimeter will give more accurate readings compared to mobile applications and GPS.

## The highest and lowest land area above sea level

If we talk about the highest and lowest points on a global scale, then Mount Everest, the real name Chomolungma, belongs to the first. It is located in the Himalayan mountain system at an altitude of 8848 m above sea level. The second peak of the mountain rises at an altitude of 8760 metro.

Everest is a clear winner among all the mountains of the planet in terms of elevation. As far back as the 19th century, a geodetic service worker Radhanat Sykdar from India measured its height. But since then, the data has changed, and the mountain was even higher than originally stated.

The lowest point above sea level is not one, but two at once. The first is on land. This is the coast of the Dead Sea on the border of Israel and Jordan. The point is located at the mark of 417 meters below sea level, but as experts say, every year this indicator increases by 1 meter.

The second point is called the Mariana Trench and is located deep under the waters of the Pacific Ocean. This is a bottomless crater, which at its lowest point has a depth of more than 11 thousand meters below sea level.

## The dependence of pressure on height above sea level

At different heights, atmospheric pressure will also vary. Many people regularly face the problem of the close relationship of poor health and fluctuations in atmospheric parameters. For this reason, it is impossible to make trips to the mountains and fly on airplanes, especially over long distances.

As the researchers say, the dependence of pressure on the height above sea level is determined by such indicators: an increase of 10 meters causes a decrease in pressure by one mark, i.e. for every 100 m, an average of 7.5 mm is reduced. Hg st. While the height does not reach 500 meters, the changes are not felt, but if you climb 5 kilometers, the values ​​will be half the optimum, which will affect your well-being. This happens because of diluted air and a decrease in the amount of oxygen necessary for living organisms.