New height above sea level. What is altitude

When it comes to viewing Google maps, the "map/terrain" mode is sometimes mentioned, in which the unevenness of the land is highlighted by changing color tones. In this map mode, valleys and mountain ranges are clearly distinguished, with height levels plotted. But if you need to determine the height at a certain point from the picture on the map, or the height above sea level in the valley, this is quite difficult to do.

Therefore, we will use the auxiliary program for, which determines not only the geographical coordinates (longitude and latitude), but also the height above sea level. This map can be switched to "relief" mode, find the desired peak and determine its height.

With this online program, you can not only determine the height of mountain peaks. If you have never wondered how high above sea level the area you live in is, then you will be surprised by the results of your measurements on the map.

Like Google map program Google Earth also able to determine the height of the area above sea level. In this program, the height is determined dynamically for the coordinates under the mouse pointer.

For information. You can determine the height above sea level using an aneroid barometer, which will show 760 millimeters of mercury at zero altitude at a temperature of 15 ° C. At an altitude of 500 meters above sea level, the barometer will show 720 mm, 1000 meters - 670 mm Hg and so on. As altitude increases, atmospheric pressure drops by about 8 mm Hg. Art. for every 100 meters of ascent. And the higher the altitude, the lower the atmospheric pressure and the concentration of oxygen in the air. For example, at an altitude of 3500 m, the atmospheric pressure is 1.5 times less than at zero altitude, respectively, and less oxygen saturation of the air.

For some people, a height of 800 meters is already reflected in their well-being. Therefore, when planning a travel route on a map from a satellite, it is necessary to pay attention to the height of the terrain. On the other hand, there are many high mountain resorts located higher than 1500 meters above sea level.

The Google Earth image shows the location on the screen of the block for displaying current altitude information. In the program options, the 3D View/Units of Measurement block contains the choice of units of measurement meters/kilometers or feet/miles.

Of course, you can determine the height using an aneroid barometer, a GPS navigator, or use both at the same time as two different devices or as two devices in one, for example, the Samsung Galaxy Nexus smartphone, which has both a GPS navigator and a barometer. But the disadvantage is that such devices must be made directly in the area being measured and these devices must be available. And if you just have to travel or you are taking height measurements to expand your own horizons, then the easiest way is to use Google Earth or. Indeed, in this case, in order to determine the height, simply click on the point found on the satellite map.

Another argument in favor of measuring on a map is that in order to determine geographic coordinates and altitude above sea level, there is no need to independently determine and calculate values using a barometer, tables or formulas. After all, for a person not connected with the need for accurate metrological measurements, the result determined by a satellite map is quite enough.

But if you need to specifically determine the height at which the office, apartment or roof of the house is located above sea level, then you will have to do the measurements yourself. It is possible to determine the height above sea level on a satellite map of any area on Earth, but the height of structures cannot be determined. Even if a specific building is selected, you will only get information about the height of the terrain. And further. If a point is found on a planet that does not have altitude data in the Google service, then the program calculates the average value calculated from the four nearest coordinates for which the altitude is determined. But the deviation from the actual value may be insignificant. It should also be noted that with the help of this service it is also possible to determine the depths of oceans and seas. In this case, the calculated height will be represented with negative values, that is, the depth is determined.

Information coordinates:
A piece of land that is below sea level

How to determine the height of a city above sea level?

The other day I was asked about the altitude at which the Crimean cities of Yalta, Alushta and Simferopol are located. At first I wanted to dismiss this question, but curiosity prompted me to check what the Internet writes on this topic.

It turned out that it is almost impossible to find references to the height of most cities of the former Soviet Union on the net. Struck by this fact, I decided to correct the situation.

To begin with, I climbed into Wikipedia and made inquiries about what the height above sea level is and from which sea it should be considered. Here is what they write there:

Height above sea level- a coordinate in three-dimensional space (the other two are latitude and longitude), showing at what level, relative to the sea level taken as zero, this or that object is located.

Baltic height system(BSV) - the system of absolute heights adopted in the USSR in 1977, which is counted from zero footstock in Kronstadt. From this mark, the heights of reference geodetic points are counted, which are marked on the ground with various geodetic signs and plotted on maps. At present, the BSV is used in Russia and a number of other CIS countries.

In theory, everything is clear - you need to take a detailed topographic map and see what heights are indicated there. But where did she get this card?

The first thing that came to mind was to look into OziExplorer. This is a special program for working with GPS (satellite navigator). One of its functions allows you to determine the height simply by pointing the cursor at a place on the map. With her help, I easily found out that Alushta is located at altitudes from 0 to 130 meters above sea level. Yalta - from 0 to 200 meters, Sevastopol - from 0 to 100, Simferopol - an average of 250 meters above sea level.

However, this method is not very versatile. After all, the question still remains “where to get a map?”, This time digitized. I had maps of Crimea, but it didn’t work out with the rest of the world ...

The answer literally lay on the surface, that is, on the Internet. It's not the first year that the service has been operating there. Google Earth- a kind of digital globe, glued together from photographs of the earth's surface from a "space" height. There must be a function for determining the height. I downloaded the distribution of Google Earth (free version), installed it and started exploring the menu. There were no altimeters. Strange ... Maybe you need to read the help? Didn't find it either.

Already almost desperate, I suddenly noticed numbers running fast at the bottom of the screen. Eureka! This was the altimeter.

To celebrate, I began to run around the map and measure the height of all the cities in a row.

The height of Yekaterinburg above sea level is 250 meters.
The height of Moscow above sea level is 130 meters.
Saratov - 40
Makhachkala - 15
Krasnoyarsk - 140
Perm — 150
Chelyabinsk - 250
Ufa - 125
Kazan - 90
Nizhny Novgorod - 70
Ivanovo - 130
Yaroslavl - 98
Voronezh - 104
Petersburg - 13
Arkhangelsk - 7
Novgorod - 28
Murom - 105

Altitude above sea level of some cities of Ukraine:

The height of Kyiv above sea level is from 90 (the level of the Dnieper) to 190 (the famous Dnieper steeps) meters.
Kharkiv - 122
Chernivtsi - 240
Khmelnitsky - 299
Ternopil - 336
Vinnitsa - 294
Cherkasy - 80
Krivoy Rog - 85
Zaporozhye — 75
Kherson - 50
Donetsk - 241
Dnepropetrovsk - 68
Sumy — 125
Poltava - 150
Chernihiv - 117

In the western part of Ukraine, I was interested in the heights of such settlements:

Lviv - 270
Ivano-Frankivsk - 343
Uzhgorod - 187
Mukachevo - 181
Rakhiv - 430
Yasinya - 650
Yablonitsky pass - 930

I hope you understand that all the data received is not too accurate. Google Earth is not a professional tool with guaranteed accuracy and reliably known errors. She has very different goals.

In addition, the very term "height of the city above sea level" is very conditional. After all, a city is not a point, but a huge object, different areas of which have different heights.

How are heights measured?

This question is followed by related ones. What is absolute and relative height? Why are there triangulation marks on the tops? When was the height first determined? What does "above sea level" mean? Does this level fluctuate? How is altitude measured from aircraft? What are command points?

Displaying the area in a reduced form on diagrams and maps, people have always paid attention to the mountains. They were conspicuous and necessary reference points. The geographical map did not appear immediately: it went through its development from clay, parchment, birch bark samples to perfect cartographic models. At first, much depended on the draftsman, his sense of space, his ability to mentally survey the Earth from a height. The mathematical reliability of the relief, of course, was absent.

Over time, the profession of renter appeared. A measuring cord, a measuring wheel, a compass went into action. In the 16th century, prototypes of measuring geodetic instruments were invented - a measuring scale, a theodolite, then - rangefinders, levels. To measure the height of the mountain, or, as topographers say, "to take vertical marks", physicists helped.

Blaise Pascal asked his acquaintances in Clermont to climb Mount Puy-de-Dome with a mercury pipe. The scientist's assumption was confirmed at a height: the mercury column dropped. Since then, it has become customary to measure the height of the area using a mercury barometer. Appeared devices for determining the height of the temperature of the vapor of boiling water: hypsometer, thermobarometer, hypsothermometer. The principle of operation is as follows: as you rise, the air pressure decreases. At the same time, the boiling point of water also decreases - about 0.27 mm of mercury column. According to the tables, atmospheric pressure is noted accordingly, and the height of the terrain is determined from it.

This is, one might say, a "field" method. But not every peak is so easy to climb for measurement. And in the 17th century, the Dutch astronomer Snellius proposed a triangulation method, when heights are determined “from the side”, using reference points. This method is also used for topographic surveys from aircraft and artificial satellites.

Altitude marks of peaks began to be distinguished: absolute - from sea level and relative - from the foot of the mountain, from the underlying plain. It is clear that the absolute heights of mountains are always greater than the relative ones. For the unity of the measurement system in geographical science, it is customary to count these measurements from the level of the World Ocean. So, after indicating the height, a conspicuous prefix “above sea level” appeared, or if it is not there, then it is simply implied. But we know the ebb and flow. The levels of the seas are unstable: they began to be distinguished: instantaneous, tidal, average daily, average annual, average long-term. This latter, according to the developed international agreements, has become the most stable in order to "tie" the height of the mountains to it.

It is clear that many peaks and ridges in the oceans that do not come to the surface are measured differently. The highest marine seamount ever discovered was in 1953 near the Tonga Trench off New Zealand. It rises from the bottom of the sea to 8690 m, and its peak is 365 m below the surface of the water. And if we do not proceed from sea level, but measure the height from the underwater base, then the highest mountain in the world is Mauna Kea (“White Mountain”) in the Hawaiian Islands. Its total height is 10,203 m, of which only 4,205 m are above sea level.

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 of defining it.

Sea level, relative to which the distance to an object is measured, is the water surface at rest, which is perpendicular to the resultant forces applied to the body of water. The water level changes very often and this is due to the phases of the moon, the strength of the sun and wind, and evaporation. Therefore, to calculate the average value, it is necessary to conduct the necessary calculations for years.

Height above sea level is a point (coordinate) in a three-dimensional area that indicates at what height a certain object is in relation to sea level, taken as zero. Also, it can be roughly defined as the vertical from the object to the mean height above sea level, without taking into account the tides. The height of a point located above the level is considered positive, below - negative. The other two coordinates of the geographic location of the object are 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 find the altitude above sea level

In the old-fashioned way, the height above sea level can be viewed in special topographic maps, which display all heights. But there are more modern methods.

You can find out what height above sea level using a satellite navigator running on a specific program, for example, Google or Google Earth (Google Earth). First you need to download one of the applications on your smartphone or computer and use the prompts to determine the distance from sea level to the object you need. Working with the programs is very simple: point the cursor at the right place on the map, and the information is displayed automatically.
Measurement of the level of a specific area is available on GPS devices. Instruments determine heights based on information received from satellites. GPS-receivers with a built-in barometer-altimeter have the highest accuracy of indicators.
In the search bar of the Yandex browser, drive in “height above sea level” and the city, country, mountain, etc. you need. This information will be especially useful for travelers who are going to conquer mountain peaks. So you can know in advance what heights you will have to overcome and prepare for the ascent.
How to determine the height knows an application 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 discrepancy of one and a half to two divisions.

Also, measurements of the height of the terrain above sea level can be carried out using an altimeter - an instrument that is used to measure the height of a rise or a point above sea level. Using the altimeter is very simple:

start the device and determine the value of blood pressure corresponding to the current weather conditions;
calibrate the device and hold the "Set" button. After that, the device will automatically switch to the desired mode and indicate the altitude pressure in the current time;
reduce the readings to normal using the "Set" button. After saving the obtained parameters in the main menu, the screen will display the height above sea level of the desired object.

Altimeter - a device for measuring altitude above sea level

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

Highest and lowest piece of land above sea level

If we talk about the highest and lowest points on a global scale, then Mount Everest, the real name of 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 meters.

Everest is a clear winner among all the mountains of the planet in terms of elevation. Back in the 19th century, a geodetic service worker Radhanat Sikdar from India measured its height. But since then, the data has changed, and the mountain turned out to be even higher than originally stated.

The lowest point above sea level is considered 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 around 417 meters below sea level, but as experts say, every year this figure 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.

Dependence of pressure on height above sea level

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

According to the researchers, the dependence of pressure on 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, there is an average decrease of 7.5 mm. rt. Art. Until the altitude reaches 500 meters, no changes are felt, but once you climb 5 kilometers, the values \u200b\u200bare half the optimal, which will affect your well-being. This happens due to liquefied air and a decrease in the amount of oxygen necessary for living organisms.