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, the 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 survived 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 the 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.
The highest capital in the world is the capital of Mexico (Mexico City). It is located at an altitude of just over two thousand two hundred meters above the level. Do you know the height of your city above sea level?
What might it be useful for? For example, to calculate the atomospheric pressure.
And from knowing the pressure, you can find out, for example, when, in which city the water will boil faster and where it will be hotter (when it boils). Again, there are rumors that the higher you live (for example, in the mountains), the longer you live.
Although, in my opinion, centenarians in the mountains simply do not have crazy neighbors who listen to music at night or work as a puncher in the morning.
But if it is easier for us to live because our city is higher than others, then so be it.
Regarding the accuracy of altitude calculations, this is for the Google API.
For example, Yandex has completely different data. For example, if we take the city of Ufa, but our bot (taking data from google) believes that the city is located at an altitude of 176.39 meters above sea level, and Yandex is 136.7 meters. So, between the two search engines there was a "small" error of 40 meters.
But there are no such discrepancies in Saratov.
Which of the two of them to believe, I will leave to your discretion. Faith is a delicate matter.
Where else can the result be used?
Again, the height above sea level will allow us to calculate, for example, how far we can see what is there on the horizon ..
In addition, the bot will calculate the radius vector for you from the center of the Earth to sea level using the formula, in kilometers
The radius vector that the bot considers takes into account in its result, including the height at sea level, for a particular settlement.
By the way, relative to which sea is the height measured, where is the zero point relative to which they consider what is the strength of the tide, or how much has the level of one or another part of the ocean risen?
The Baltic Sea is considered to be the generally accepted one, since it is least of all subject to tides and currents. There are several such places, the level of which can be taken as a zero point, on Earth, but all of them are points somewhere where there is no civilization, or land in general.
Let's calculate several cities for example.
Vladivostok
| The resulting height of the object at sea level, in meters |