World sea levels are rising much faster than it seems. Determining the height of peaks above sea level or the depth of oceans and seas

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Height above sea level, absolute altitude, absolute elevation or altitude(lat. altitudo- height (points of the earth's surface above ocean level)) - one coordinate in three-dimensional geospace (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.

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• // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
• - article from the Great Soviet Encyclopedia (3rd edition)

Excerpt describing Altitude above sea level

When talking about viewing Google Maps, people sometimes mention the map/terrain mode, which highlights land features by changing color tones. In this map mode, valleys and mountain ranges are clearly distinguished, with elevation levels plotted. But if you need to determine the height at a certain point from a picture on a map, or the height above sea level in a valley, this is quite difficult to do.

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

Using 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 before, then you will be surprised by the results of your measurements on the map.

Like Google map program Google Earth also knows how 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 altitude 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. With increasing altitude above sea level, the atmospheric pressure drops by approximately 8 mmHg. Art. for every 100 meters of ascent. And the higher the altitude, the lower the atmospheric pressure and oxygen concentration in the air. For example, at an altitude of 3500 m, the atmospheric pressure is 1.5 times less than at zero altitude, and accordingly, the oxygen saturation of the air is lower.

For some people, an altitude of 800 meters already affects their well-being. Therefore, when planning a travel route using a satellite map, you need to pay attention to the altitude of the area. 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 displaying current altitude information. In the program options, the 3D View/Units of Measurement block contains a choice of units of measurement: meters/kilometers or feet/miles.

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

Another argument in favor of measuring using a map is that 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 concerned with the need for precise metrological measurements, the result determined from a satellite map is quite sufficient.

But if you need to specifically determine the height at which your office, apartment or house roof is located above sea level, then you will have to take measurements yourself. You can determine the height above sea level from a satellite map of any area on Earth, but the height of buildings cannot be determined. Even if a specific building is selected, you will only receive information about the elevation of the area. And further. If a point is found on the planet that does not have altitude data in the Google service, then the program calculates the average value calculated from the four closest coordinates for which the altitude is determined. But the deviation from the actual value may be insignificant. You should also pay attention to the fact that using this service you can also determine the depths of oceans and seas. In this case, the calculated height will be presented with negative values, that is, the depth is determined.

Coordinates for information:
An area of ​​land that is below sea level

To begin with, let's remember the high school physics course, which explains why and how atmospheric pressure changes depending on altitude. The higher the area is above sea level, the lower the pressure there. It is very simple to explain: atmospheric pressure indicates the force with which a column of air presses on everything that is on the surface of the Earth. Naturally, the higher you rise, the lower the height of the air column, its mass and the pressure exerted will be.

In addition, at altitude the air is rarefied, it contains a much smaller number of gas molecules, which also immediately affects the mass. And we must not forget that with increasing altitude, the air is cleared of toxic impurities, exhaust gases and other “delights”, as a result of which its density decreases and atmospheric pressure drops.

Studies have shown that the dependence of atmospheric pressure on altitude differs as follows: an increase of ten meters causes a decrease in the parameter by one unit. As long as the altitude of the area does not exceed five hundred meters above sea level, changes in the pressure of the air column are practically not felt, but if you rise five kilometers, the values ​​​​will be half the optimal ones. The strength of the pressure exerted by the air also depends on the temperature, which decreases greatly when rising to a higher altitude.

For the level of blood pressure and the general condition of the human body, the value of not only atmospheric pressure, but also partial pressure, which depends on the concentration of oxygen in the air, is very important. In proportion to the decrease in air pressure, the partial pressure of oxygen also decreases, which leads to an insufficient supply of this essential element to the cells and tissues of the body and the development of hypoxia. This is explained by the fact that the diffusion of oxygen into the blood and its subsequent transportation to the internal organs occurs due to the difference in the partial pressure of the blood and the pulmonary alveoli, and when rising to a high altitude, the difference in these readings becomes significantly smaller.

How does altitude affect a person's well-being?

The main negative factor affecting the human body at altitude is the lack of oxygen. It is as a result of hypoxia that acute disorders of the heart and blood vessels, increased blood pressure, digestive disorders and a number of other pathologies develop.

Hypertensive patients and people prone to pressure surges should not climb high into the mountains and it is advisable not to take long flights. They will also have to forget about professional mountaineering and mountain tourism.

The severity of the changes occurring in the body made it possible to distinguish several altitude zones:

• Up to one and a half to two kilometers above sea level is a relatively safe zone in which no special changes are observed in the functioning of the body and the state of vital systems. Deterioration in well-being, decreased activity and endurance are observed very rarely.
• From two to four kilometers - the body tries to cope with the oxygen deficiency on its own, thanks to increased breathing and taking deep breaths. Heavy physical work, which requires the consumption of large amounts of oxygen, is difficult to perform, but light exercise is well tolerated for several hours.
• From four to five and a half kilometers - the state of health noticeably worsens, performing physical work is difficult. Psycho-emotional disorders appear in the form of high spirits, euphoria, and inappropriate actions. When staying at such a height for a long time, headaches, a feeling of heaviness in the head, problems with concentration, and lethargy occur.
• From five and a half to eight kilometers - it is impossible to do physical work, the condition worsens sharply, the percentage of loss of consciousness is high.
• Above eight kilometers - at this altitude a person is able to maintain consciousness for a maximum of several minutes, after which deep fainting and death follows.

For metabolic processes to occur in the body, oxygen is necessary, the deficiency of which at altitude leads to the development of altitude sickness. The main symptoms of the disorder are:

• Headache.
• Increased breathing, shortness of breath, lack of air.
• Nose bleed.
• Nausea, attacks of vomiting.
• Joint and muscle pain.
• Sleep disorders.
• Psycho-emotional disorders.

At high altitudes, the body begins to experience a lack of oxygen, as a result of which the functioning of the heart and blood vessels is disrupted, arterial and intracranial pressure increases, and vital internal organs fail. To successfully overcome hypoxia, you need to include nuts, bananas, chocolate, cereals, and fruit juices in your diet.

Effect of altitude on blood pressure levels

When rising to a high altitude, thin air causes an increase in heart rate and an increase in blood pressure. However, with a further increase in altitude, blood pressure levels begin to decrease. A decrease in the oxygen content in the air to critical values ​​causes depression of cardiac activity and a noticeable decrease in pressure in the arteries, while in the venous vessels the levels increase. As a result, a person develops arrhythmia and cyanosis.

Not long ago, a group of Italian researchers decided for the first time to study in detail how altitude affects blood pressure levels. To conduct research, an expedition to Everest was organized, during which the participants’ pressure levels were determined every twenty minutes. During the hike, an increase in blood pressure during ascent was confirmed: the results showed that the systolic value increased by fifteen, and the diastolic value by ten units. It was noted that the maximum blood pressure values ​​were determined at night. The effect of antihypertensive drugs at different altitudes was also studied. It turned out that the drug under study effectively helped at an altitude of up to three and a half kilometers, and when rising above five and a half it became absolutely useless.

Sea level rise was thought to have slowed over the past 20 years. However, new research from University of Tasmania surveyors has found these calculations are wrong. A group of scientists led by Christopher Watson published figures in the journal Nature Climate Change showing that there is in fact no slowdown - sea levels are rising much faster than previously thought. Previous studies have shown that sea levels have risen by about 3.2 mm per year each year since 1993, but the actual figure may be underestimated due to imperfect estimation techniques, scientists say.

This means that many geographic locations will be at risk of flooding. “Russian Planet” has compiled a rating of the most significant places that could go under water already in this century. Among them are the most beautiful islands, as well as large cities: alas, our civilization developed largely thanks to navigation, and many luxurious metropolises are located on the shores of the oceans and seas, at a low altitude above sea level.

1. Maldives

Situated in the warm waters of the Indian Ocean, the islands, which many travelers perceive as an earthly paradise, have an average height above sea level of 1.5 meters. This means that by about 2100, their population, mainly living on the coast, will be forced to leave their homes. The islands are of coral origin, and the depth of the ocean around them is low: when the atolls disappear under water, they will be visible from the air as vast shallows. Along with the archipelago, its exceptionally rich fauna will also perish.

2. Bangladesh

In this country, floods serve as a political factor: they are usually followed by famine (since water destroys not only people, but also crops), and this leads to crises of confidence in the authorities. This was the case in 1974, when, due to a catastrophic flood in which 2 thousand people died, 1 million were injured, and several million more were left homeless, the government was forced to introduce martial law. The largest flood happened relatively recently - in September 1998, due to the flood of the Ganges, Brahmaputra and Meghna, about 300 thousand houses were flooded. Due to rising sea levels, researchers predict an increase in river water area and flooding of the sea coasts of Bangladesh. By the end of the century, half the country will be the bottom of a “sea” only one meter deep. Of course, it will most likely not be a sea, but a swamp covered with thickets of trees and bushes.

Flood in Bangladesh. Photo: Abir Abdullah / EPA / TASS

3. New Orleans

The birthplace of jazz is located below sea level: in different quarters of the city the figure varies from 1.5 to 3 meters. The city is saved by dams built after the Flood Control Act was passed in 1965. However, the dams turned out to be not as reliable protection as the engineers who built them believed. On August 29, 2005, Hurricane Katrina caused water to breach one of them, while waves were able to move through a number of others. As a result, more than 80% of the city's area was under water. If sea levels rise, within a few decades the city will become an easy victim for hurricanes, which could be even 1.5-2 times weaker than Katrina.

4. New York

Like New Orleans, this American metropolis has suffered from hurricanes more than once in its history: in 2012, Hurricane Sandy killed 185 local residents. Some parts of the city went under water. Eight months after the disaster, Mayor Michael Bloomberg unveiled a $19.5 billion plan to protect New York from natural disasters, one of the main elements of which would be the strengthening of coastlines. If the large-scale project is not implemented, Long Island and the lower Hudson River Valley could be under water by 2080.

5. Bangkok

Is Bangkok half empty or half full? According to the most pessimistic expert estimates, part of the capital of Thailand will go under water as early as the 2030s: in addition to rising sea levels, coastal erosion is working towards the death of the city. A giant dam along the Gulf of Thailand could save the city. But if in the case of New York or New Orleans there is hope for the construction of such giant dams, then the peculiarities of the political situation in the country will most likely not allow a national project to save the city. Now more than a million houses, 90% of which are residential, are at risk; most likely, over time, their first floors will begin to be periodically flooded.

Consequences of heavy rains in Thailand. Photo: Narong Sangnak / EPA / TASS

Another beautiful American city, famous for its beaches, may become a victim of the waves of the Atlantic. The foundation of the city is formed by limestone rocks, which allow water to pass through well, which means that the construction of dams, which could help New York, will be completely useless here. It is possible that by the end of the century the city will have to move the residents of some neighborhoods to higher places: the metropolis will, as it were, “crawl” further and higher from the ocean line.

7. Venice

One of the most romantic cities in the world will disappear in the waves if the level of the world's oceans rises “at least” by one meter. The city had already been hit by massive floods in 2008, causing tens of millions of dollars in damage to buildings. As experts from the World Wildlife Fund noted earlier, Italy as a whole may lose many of its beaches, resorts and unique coastal flora and fauna. About 60% of Italians live near sea coasts, and coastal erosion has led to the disappearance of 42% of the country's beaches over the past quarter century.

8. Amsterdam

This city was already reclaimed from nature: a third of it is an artificial embankment that was built over several centuries. The name of the city itself, by the way, reflects this fact - it translates as “Amstel dam”, “dam on the Amstel River”. Perhaps it’s time to repay nature’s debts: if the water rises two meters, the city will almost completely go under water. This could happen by the middle of the next century, but even in this century, large parts of the city could be at the mercy of the waves.

9. Shanghai

The name of this city literally means "by the sea", and such a location is fraught with a certain danger. The average height of the city above sea level is quite high - 6.5 meters, but there are “lowlands” on its territory, and the number of citizens living in them would be an honor for a large European city - approximately 5.5 million people. The situation is also complicated by the fact that the city has almost no flood protection system: the authorities have only recently begun to think about its need. In general, Shanghai is far from the only city in China that is threatened by rising sea levels: vast areas of cities such as Guangzhou or Hong Kong are located below sea level.

10. Hamburg

Climate change has forced the city, Germany's second largest, to deal with storm surges, rising sea levels and unusual heat in the past few years. Although flood control systems have a long tradition here - the first dams were built in the Middle Ages - their development may not keep pace with rising sea levels. Now the low areas of the city adjacent to the Elbe are protected by a continuous dam 14.5 m high on both sides of the river. If the planet's climate continues to change at the same rate as it is now, this powerful dam may no longer serve as a reliable cover for the city.

Flood in Hamburg. Photo: Kay Nietfeld / DPA / TASS

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

The other day I was asked at what altitude above sea level are the Crimean cities of Yalta, Alushta and Simferopol. At first I wanted to brush this question aside, but curiosity prompted me to check what the Internet was writing on this topic.

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

To begin with, I went to Wikipedia and made inquiries about what altitude above sea level is and from which sea it should be calculated. Here's 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) is a system of absolute altitudes adopted in the USSR in 1977, which is counted from the ground zero in Kronstadt. The heights of reference geodetic points are measured from this mark, which are marked on the ground with various geodetic signs and plotted on maps. Currently, 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 can I 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 - on average 250 meters above sea level.

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

The answer literally lay on the surface, that is, on the Internet. This is 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 “cosmic” height. There certainly should be a height detection function. I downloaded the Google Earth distribution (free version), installed it and started exploring the menu. There were no altimeters there. Strange... Maybe I should read the certificate? I didn't find it either.

Almost in despair, I suddenly noticed numbers quickly running 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
• St. Petersburg - 13
• Arkhangelsk - 7
• Novgorod — 28
• Murom - 105

Altitude above sea level of some cities in Ukraine:

• The height of Kyiv above sea level is from 90 (the level of the Dnieper) to 190 (the famous Dnieper steeps) meters.
• Kharkov - 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
• Yablunytsky pass – 930

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

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