Absolute and relative marks in geodesy. What is relative and absolute height

Instruction

On the geographical map relief is depicted using special ( mountains isontals) that connect points of the terrain with the same absolute height. To get an idea of ​​the landforms, you need several mountains isontals. Pay attention to the map - mountains isontals are drawn at certain intervals of height, depending on the scale. The vertex is denoted by a dot and signed by its absolute height. The closer mountains isontals are located from each other, the steeper the slope, and vice versa. Consider mountains isontals, you will see short lines (berghatches) with them indicating the direction of the slope.

Learn another way to depict relief. This is the so-called layered coloring. Traditionally, yellow-brown and gamma are used for it. The higher the terrain, the darker the color. Successfully executed layer-by-layer coloring creates the effect of relief convexity on map without complicating the perception of its content.

So, to determine the absolute height object located on the surface, compare the color of this fragment of the map with the scale of heights and depths shown on the margins of the map. A plain up to 200 m above sea level is also a bright in green. Plains 500-1000 m high (flat mountains e) are light brown in color. The same land areas that are located below sea level are indicated by map in dark green, and their height with a minus sign.

To determine the height mountains compare their brown-red coloration with the height scale. The higher mountains s, the darker and richer the shade. Mountains up to 1000 m high have a light brown color on map. Medium mountains s (1000-2000 m high) look at map brighter. More significant elevations of the earth's surface are painted in bright red.

look at map mountains new array and select the black dots marked on it. This is how the highest peaks of the massif are designated, the name is signed next to it and accurate to the nearest meter.

Sources:

• Image of land and waters on the map
• What is the absolute height of the highest point of the andes

Gathering in the mountains, take an altimeter (altimeter) with you, which will allow you to always be informed about the height of your location. It is important to know this not only for orientation, but for controlling your physical condition.

You will need

• - mechanical or electronic altimeter.

Instruction

Use an altimeter to determine the surrounding mountains. The mechanical instrument is based on the simple principle of atmospheric pressure as a function of altitude. The pressure drops with increasing height, the spring in the device unwinds and the arrow height with an accuracy of 1 m, depending on the number of divisions on the dial. Now there are electronic altimeters.

Produce heights with a mechanical instrument. Set the arrow to 0 before the start of the ascent, the device will height which you climbed. Please note that weather conditions greatly affect the readings of the device. If during for the atmospheric pressure changes sharply, it is necessary to reconfigure.

Use electronic altimeters, which are often built into watches and are very convenient for hiking. In special ones for determining the height, not only the height above sea level is indicated, but also the air temperature and time. For use, it is necessary to set the starting point of measurement, as in a mechanical device, and fix the point at an altitude (such devices are also based on the principle of the relationship of atmospheric pressure with altitude above sea level).

Unfortunately, it is not possible to use systems for determining absolute, and not relative height (as mentioned above), until they are released for general use. These are devices that use the reflection of radio waves, gamma radiation, and GPS receivers. A radio altimeter measures the time of reflection of the sent wave from the surface of the earth or water and calculates the distance. A GPS receiver determines a point in space using the signals it receives from the Earth. It defines more precisely height, since these signals are independent of weather conditions and distance measurements from the earth's surface.

Sources:

• Parachute altimeters: mechanical and electronic in 2019

Any location in space geographic point It is customary to determine by its coordinates: latitude, longitude and height. Altitude relative to sea level and determines height plains, mountains, any point on the surface of the Earth.

Instruction

Height above sea level (altitude) is a conditional geographical coordinate of the object's location along a vertical line. Mountains and ravines can be above and below the height above sea level, but the conditional point of the sea surface is taken as absolute. It is impossible to accurately determine the sea level due to the tides, so the average annual surface coordinate is usually calculated. In Russia, the absolute zero of the altitude is taken to be the level of the Baltic Sea, determined from the zero of the Kronstadt footstock.

Self-altitude is impossible for ordinary Earth. This task is only possible for the exploration of a specially trained geophysical team, and more recently - electronic systems calculation of coordinates. Many computer programs will help to cope with the task of determining the height above sea level in. For example, in the program Google Planet Earth" geographical coordinates (height, latitude and) are displayed by default at the bottom of the screen with the mouse. That is, if you hover over a specific geographical object, the program will automatically determine its altitude.
Car GPS devices also have the function of determining the height above sea level.

So in order to determine height plains or any other geographical feature, please refer to professional help geophysicists or resort to electronic computing satellite navigation. It is almost impossible to calculate this value on your own. The height of a particular point on the surface of the globe can be found in an academic geographical publication - for example, an atlas.

Useful advice

Interesting Facts.
The land area above sea level is 148,021,000 sq. km (148,021,000 sq. miles).
The area of ​​all seas is 362,033,000 sq. km (139,782,000 miles).
The highest point on land is Mount Everest in the Himalayas, its height is 8844.43 meters above sea level.
The lowest piece of land - the coast Dead Sea, it is 417.5 meters below sea level.

As well as when carrying out work on the geological study of a subsoil area, in some documents, along with the coordinates, it is necessary to indicate the absolute mark of the wellhead.

What is the absolute mark of the wellhead?

Let's break the question down into two parts:

1) First, let's figure out where the mouth of the well is?

For the wellhead should take the edge casing pipe, protruding from the ground, or a pump base plate that closes the well from above.

2) What is an absolute mark?

Absolute mark or altitude (lat. altitude) - 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. In relation to the territory of the Russian Federation, the height above the level of the Baltic Sea (Baltic system of heights) is taken as an absolute mark.

If you, let's say, went to school, then in geography lessons you should have seen maps covered with a network of brown curved lines. These lines are especially thick in areas depicting mountainous relief. So these lines are called "isohypses", i.e. lines of equal marks. They just show the height above sea level. Again, you should be aware of the fact that the height of the high mountain Everest is 8,848 m. So, the number 8,848 is the absolute mark of the peak.

How to determine the absolute mark of the wellhead?

There are three ways.

The first way is to find the value of the absolute mark in the well passport. Usually, the mark is defined in it with an accuracy of 1 m. I won’t say that this accuracy was sufficient, but it’s quite suitable for paperwork.

The second way is to take any overview map that contains your site with a well and relief isohypses, and remove the mark from the map using the interpolation method. You can use any terrain plans at a scale of 1:500 and smaller, on which the marks of the objects closest to the well are marked. Don't know what interpolation is? Never worked with topographical plans? Then - let's go! Option two - delete.

The third way is to contact the geodetic organization with a request to determine the absolute mark of the wellhead. If the surveyors run the theodolite traverse from the nearest MZ (reference markers), they will give you an exact absolute mark of the wellhead with an error of no more than 10 cm.

What should not be done in any case is to determine the absolute mark using a GPS navigator. If the accuracy of determining geographic coordinates for modern receivers can reach plus or minus 4 m, then things are very bad with determining the height. Usually, the height is determined by the barometric method (depending on atmospheric pressure), as a result, the results of measurements taken in bad weather and on a sunny day may differ by several tens of meters. It is impossible to insert such a mess into official documents.

And, generally speaking, there is a fourth option.

When licensing wells, you, in any case, will have to contact a specialized organization that will help with paperwork and carry out work on the geological study of the subsoil area in order to calculate reserves groundwater. So let it be at the expense of the absolute mark - their head hurts!

NPG "Tektonika". We

ABSOLUTE MARK

ABSOLUTE MARK

a number indicating the height of the point above the level; sea ​​in meters (see absolute height). A. o. plotted on topographic maps horizontal lines.

In railway. In fact, these cards are used for cameral tracing lines.

Technical railway dictionary. - M.: State transport railway publishing house. N. N. Vasiliev, O. N. Isaakyan, N. O. Roginsky, Ya. B. Smolyansky, V. A. Sokovich, T. S. Khachaturov. 1941 .

See what "ABSOLUTE MARK" is in other dictionaries:

1) Absolute height, absolute mark or altitude (lat. altitude (in geodesy) vertical distance (in meters) from any point on the surface of the Earth to the average level of the ocean surface, not disturbed by waves and tides ... Wikipedia

An absolute elevation (in geodesy), the vertical distance from any point on the Earth's surface to the mean level of the ocean's surface. Determined by Leveling. In the USSR, A. v. calculated from zero footstock in Kronstadt ... Great Soviet Encyclopedia

- (abs., relative) convoy, abs. or the relative height of the terrain in numbers (m, feet, etc.). The term is incorrect, it is not recommended to use it. See Height is absolute. Height is relative. Geological dictionary: in 2 volumes. M .: Nedra. ... ... Geological Encyclopedia

Forms of government, political regimes and systems Anarchy Aristocracy Bureaucracy Gerontocracy Demarchy Democracy Imitation democracy Liberal democracy Will present ... Wikipedia

Hegelianism ... Wikipedia

This article lacks links to sources of information. Information must be verifiable, otherwise it may be questioned and removed. You can ... Wikipedia

Would you like to improve this article?: Find and provide footnotes for references to authoritative sources that confirm what has been written. Supplement the article (the article is too short or contains only a dictionary definition). Pr ... Wikipedia

Altitude above sea level ... This term, perhaps, is known to every schoolchild. We often meet him in newspapers, on websites, in popular science magazines, as well as when watching documentaries.

Now let's try to give it a more precise definition.

Section 1. Altitude above sea level. general information

This term should be understood as the absolute height or absolute mark, i.e. such a coordinate in which shows at what height in relation to sea level this or that object is located.

Two other indications of the geographical location of an object are longitude and latitude.

Here, for example, Moscow. The height above sea level of this city is very different: the maximum is 255 m (not far from the metro station "Teply Stan"), and the minimum - 114.2 m - is located near the Besedinsky bridges, exactly where the Moscow River leaves the city.

In general, if we operate with purely physical measurements, then the height above sea level is nothing more than the vertical distance from, in fact, the single object itself to the average level of the sea surface, which should not be disturbed by either tides or waves.

This value can be both positive and negative. Well, everything is relatively simple here: what is above the sea acquires a plus sign, and below, respectively, a minus sign.

By the way, it is impossible not to note the fact that with an increase in its value, a decrease in atmospheric pressure is observed.

If we talk about our country, then the 5642-meter Elbrus is rightfully considered the highest land point in the Russian Federation, but the lowest can be called with an absolute height of about 28 m.

Section 2. Altitude above sea level. Most high place on the planet

Well, of course, this is Everest - a well-known mountain located in the central part of the Himalayas, just on the border of two South Asian states, Nepal and Tibet.

Today its height is 8848 meters. The words "today" are not accidental. According to scientists, the earth's surface is still continuing to form, so this peak, although imperceptibly, is growing every year.

If you delve into history, then almost immediately you can find information that the first brave conquerors of Chomolungma were (New Zealand) and Tenzing Norgay (Nepal). They made their truly heroic ascent on May 28, 1953. Since then, Everest has become a kind of Mecca for hundreds and thousands of rock climbers, climbers and other daring adventurers.

Section 3. Altitude above sea level. The lowest place on the planet

In this case, things are a little more complicated. The fact is that there are two such points on Earth at once: one of them - the coast of the Dead Sea - is located on land, and the second bears the name and is located deep under the water column of the Pacific Ocean.

Let's dwell on each of them in more detail.

So, the Dead Sea, as you know, can be found on the border of three countries: Israel, Palestine and Jordan. It is not only the most salty body of water on the planet, but the lowest piece of land.

Now the water level in it is 427 meters, but this is not the limit, because annually, according to experts, it falls by an average of 1 meter.

Altitude above sea level… Moscow, as mentioned above, is located in the range from 114 to 255 m. For us, this is, in principle, the norm. Considering that the capital of the Russian Federation can hardly be called very hilly, it is almost impossible to feel this difference.

And now let's pick up a globe or a physical map of the earth's surface: somewhere deep, deep in the Pacific Ocean, not far away, you can see a mark with the inscription So, it goes under water to a depth of a little more than 11 km.

CHAPTERIIISHELLS OF THE EARTH

Topic 1LITHOSPHERE

§24. TERRAIN ALTITUDE AND RELATIVE HEIGHT

Remember how you can measure the height of an object.

What are the surface shapes in your area?

You already know that the earth's surface is uneven. It has relatively flat areas, there are ups and downs - hills, mountains, ravines. To represent the irregularities of the earth's surface and show them on a plan or map, you need to know the height of the hills and the depth of the depressions in the surface.

HOW RELATIVE HEIGHT IS MEASURED. To determine the height of, for example, a hillock on the ground, you need to measure the vertical distance from its sole to the top. This can be done with a leveler. The level is a simple device in the form of a vertical rail 1 m high and a horizontal bar with a plumb line (drawer).

The method of measuring their height is shown in fig. 87. First, a level is installed at the bottom of the hill. Behind the plumb line, its verticality is checked. The horizontal bar of the level is directed to the slope. They “aim” in the direction of the bar and notice the point on the slope to which it is directed. A peg is hammered there. If the height of the level is 1 m, this point will be 1 m higher from where the level is located. After that, the level is transferred to the stake and "aim" at another point up the slope. The second point will already be 2 m above the sole. So sequentially rearrange the level several times along the slope. Having reached the top, the height of the hill in meters is determined by the number of pegs.

Thus, they find out how many meters one point (in our example, the top of the hill) is higher relative to the other (the bottom of the hill). The excess of one point on the earth's surface above another is called relative height.

Measurement of the height of points on the earth's surface is called leveling (Fig. 88). With the help of a level, you can measure the height of the river bank above the water, the height of the slope of the ravine above its bottom, and the like. The relative height needs to be known to scientists, builders, tourists.

School level

Rice. 87. Relative height measurements

Rice. 88. Leveling

HOW ABSOLUTE HEIGHT IS DETERMINED. If you carefully consider Fig. 88, you will see that on one slope of the hill the level was set four times, on the slope on the other side - five times. This means that the sole hump on one eye may be lower than on the other. Therefore, the relative height of the peak, measured on different sides of the hill, may not be the same.

To avoid inconsistency in heights, on plans and maps they indicate not a relative height, but an absolute one. It is measured from a single level - sea level, which is considered to be zero. Therefore, absolute height is the excess of a point on the earth's surface above sea level, which affects 0. However, different seas have different levels. Which one should be counted from? In Ukraine, as in other countries (Russia, Belarus, Moldova, etc.), it is customary to count the absolute height of surface points from the level of the Baltic Sea (Fig. 89).

To determine the absolute height of the points, it is not necessary to go to its shores. In various places on the ground, special signs are placed - benchmarks (Fig. 90). They indicate the height of this section above the level of the Baltic Sea. From this sign, by leveling, you can determine the height of any point. For example, the absolute height of Kiev (its highest part - Pechersk) is 190 m.

On plans and maps, the absolute height of a single point in the terrain is indicated by a dot.

Near it write the height in meters. This is the height mark (Fig. 92).

Rice. 89. Altitude reading

Rice. 9 0. Rapper

Rice. 91.

Rice. 93. Image of surface irregularities on a plane using contour lines

Rice. 94. Images of contour lines on the plan

HOW SURFACE IRREGULARITIES ARE SHOWN BY HORIZONTS. Roughnesses of the earth's surface on plans and maps are depicted as horizontal lines. Contours are lines on a plan or map connecting points on the earth's surface with the same absolute height. They outline the shape of the irregularities of the earth's surface. So, the marks of the absolute heights of the hill are transferred to the plan and connected by lines with other similar height marks (Fig. 93, 94).

On the plan, the horizontals are depicted by lines of pink or brown. They are carried out at certain intervals. For example, through the skin 5,10, 20, 50, 100 or 200m. On the horizontal line, the number indicates the absolute height.

Please note: the distance between contour lines depends on the steepness of the slopes. If the slope is steep, the contour lines on the plan will be drawn close to each other, if the slope is gentle - at a greater distance. Small dashes drawn perpendicular to the horizontal are called berghash. With the free end, they indicate in which direction the slope goes down. Horizontals on the plans depict not only rise, but also depressions. Then the berghashes will be directed with their free end inside the contour.

Behind the horizontals on the plan, practical issues can be resolved. For example, one has only to look at the plan to determine in which direction the terrain rises, which slope of the hill is steeper, a certain object is visible from one point or another.

Image of berghashes on contour lines

On the map, the contour lines are drawn through several meters as on the plan, and through hundreds of meters and through different intervals of height (on the map of the hemispheres - 0, 200 m, 500 m, 2000 m, etc.). For greater clarity, the area between the horizontals is painted with various colors. Sections with absolute heights from 0 to 200 m are shaded green, from 200 to 500 m - yellow, over 500 m - shades of brown. Same horizontal lines and shades blue color the depths of the oceans and seas are shown. As you already know, the colors used on the map are explained by the scale of heights and depths.

Despite the relative and absolute heights, the highest mountain in the world is not Everest (8850 m), but the Mauna Kea volcano in the Havana Islands. Its absolute height is 4205 m (above sea level), and its relative height is 9705 m (from the foot at the bottom of the ocean to the top).

REMEMBER

height is the excess of one point on the earth's surface above another.

Absolute height is the elevation of a point on the earth's surface above sea level.

Contours are lines on a plan or map connecting points of the same absolute height.

Bergstroke - a dash drawn perpendicular to the horizontal and indicates with its free end in which direction the slope goes down.

QUESTIONS AND TASKS

1. What is the difference between relative height and absolute height?

2. What does the height mark on the plan mean?

3. What do the horizontals on the plan represent?

4. Determine at what distance from each other the horizontal lines are drawn in fig. 93.

5. What is the relationship between the steepness of the slope and the distance between contour lines?

6. How does a hill differ from a depression in terms of image?

7. Calculate the relative height of the hill if its absolute height is 487 m, and the horizontal near the base is drawn at a height of 230 m.

8. How would the absolute height of Mount Hoverla change if the water level in the Baltic Sea rose by 10 m?

PRACTICAL WORK 4

Topic: Determination of the absolute and relative height of the terrain using maps.

1. Using physical card hemispheres, on a scale of heights determine:

a) the absolute height of the Brazilian plateau and its height relative to the Amazonian lowland;

b) absolute height Ural mountains and their height relative to the West Siberian Plain.

2. Using the physical map of the hemispheres, determine the height marks:

a) the absolute height of Mount Kilimanjaro in Africa;

b) the absolute height of Mount Chomolungma (Everest), which is in Asia.

Majestic mountains and endless plains, high cones of volcanoes and deep intermountain valleys, sandy hills and ravines - such diverse forms of the land surface. The irregularities of the continental and oceanic crust are very different. They are distinguished by shape, size, origin, age. There are convex forms (hills, mountains), concave (ravines, valleys, depressions), flat and hilly. The totality of the forms of the earth's surface is called relief. The varied terrain is the result of the interaction of internal processes that create irregularities, and external ones that try to even them out.

If we imagine the surface of the planet without ocean water, we will see the largest landforms of the earth's crust: the depressions of the oceans and the continents rise above them. These inequalities determine the "face" of the planet, so they are called planetary landforms (largest). And on the continents and at the bottom of the oceans, the main landforms (large) are plains and mountains. they are complicated by smaller forms - hills and valleys, hillocks and ravines, etc. (Fig. 95).

Rice. 95 Dividing landforms