Geographic coordinates of cities around the world. Geographic coordinates, latitude and longitude, how to determine geographic coordinates from a topographic map

In Chapter 1, it was noted that the Earth has the shape of a spheroid, that is, an oblate ball. Since the earth's spheroid differs very little from a sphere, this spheroid is usually called the globe. The earth rotates around an imaginary axis. The points of intersection of the imaginary axis with the globe are called poles. North geographic pole (PN) is considered to be the one from which the Earth’s own rotation is seen counterclockwise. South geographic pole (PS) - the pole opposite to the north.
If you mentally cut the globe with a plane passing through the axis (parallel to the axis) of rotation of the Earth, we get an imaginary plane called meridian plane . The line of intersection of this plane with the earth's surface is called geographical (or true) meridian .
A plane perpendicular to the earth's axis and passing through the center of the globe is called plane of the equator , and the line of intersection of this plane with the earth’s surface is equator .
If you mentally cross the globe with planes parallel to the equator, then on the surface of the Earth you get circles called parallels .
The parallels and meridians marked on globes and maps are degree mesh (Fig. 3.1). The degree grid makes it possible to determine the position of any point on the earth's surface.
It is taken as the prime meridian when compiling topographic maps Greenwich astronomical meridian , passing through the former Greenwich Observatory (near London from 1675 - 1953). Currently, the buildings of the Greenwich Observatory house a museum of astronomical and navigational instruments. The modern prime meridian passes through Hurstmonceux Castle 102.5 meters (5.31 seconds) east of the Greenwich astronomical meridian. A modern prime meridian is used for satellite navigation.

Rice. 3.1. Degree grid of the earth's surface

Coordinates - angular or linear quantities that determine the position of a point on a plane, surface or in space. To determine coordinates on the earth's surface, a point is projected as a plumb line onto an ellipsoid. To determine the position of horizontal projections of a terrain point in topography, systems are used geographical , rectangular And polar coordinates .
Geographical coordinates determine the position of the point relative to the earth's equator and one of the meridians, taken as the initial one. Geographic coordinates can be obtained from astronomical observations or geodetic measurements. In the first case they are called astronomical , in the second - geodetic . In astronomical observations, the projection of points onto the surface is carried out by plumb lines, in geodetic measurements - by normals, therefore the values ​​of astronomical and geodetic geographical coordinates are somewhat different. To create small-scale geographic maps, the compression of the Earth is neglected, and the ellipsoid of revolution is taken as a sphere. In this case, the geographic coordinates will be spherical .
Latitude - an angular value that determines the position of a point on Earth in the direction from the equator (0º) to the North Pole (+90º) or the South Pole (-90º). Latitude is measured by the central angle in the meridian plane of a given point. On globes and maps, latitude is shown using parallels.

Rice. 3.2. Geographic latitude

Longitude - an angular value that determines the position of a point on Earth in the West-East direction from the Greenwich meridian. Longitudes are counted from 0 to 180°, to the east - with a plus sign, to the west - with a minus sign. On globes and maps, latitude is shown using meridians.

Rice. 3.3. Geographic longitude

3.1.1. Spherical coordinates

Spherical geographic coordinates are called angular values ​​(latitude and longitude) that determine the position of terrain points on the surface of the earth’s sphere relative to the plane of the equator and the prime meridian.

Spherical latitude (φ) called the angle between the radius vector (the line connecting the center of the sphere and a given point) and the equatorial plane.

Spherical longitude (λ) - this is the angle between the plane of the prime meridian and the meridian plane of a given point (the plane passes through the given point and the axis of rotation).

Rice. 3.4. Geographic spherical coordinate system

In topography practice, a sphere with radius R = 6371 is used km, the surface of which is equal to the surface of the ellipsoid. On such a sphere, the arc length of the great circle is 1 minute (1852 m) called nautical mile.

3.1.2. Astronomical coordinates

Astronomical geographical coordinates are latitude and longitude that determine the position of points on geoid surface relative to the plane of the equator and the plane of one of the meridians, taken as the initial one (Fig. 3.5).

Astronomical latitude (φ) is the angle formed by a plumb line passing through a given point and a plane perpendicular to the axis of rotation of the Earth.

Plane of the astronomical meridian - a plane passing through a plumb line at a given point and parallel to the Earth’s axis of rotation.
Astronomical meridian - line of intersection of the geoid surface with the plane of the astronomical meridian.

Astronomical longitude (λ) is the dihedral angle between the plane of the astronomical meridian passing through a given point and the plane of the Greenwich meridian, taken as the initial one.

Rice. 3.5. Astronomical latitude (φ) and astronomical longitude (λ)

3.1.3. Geodetic coordinate system

IN geodetic geographic coordinate system the surface on which the positions of points are found is taken to be the surface reference -ellipsoid . The position of a point on the surface of the reference ellipsoid is determined by two angular quantities - geodetic latitude (IN) and geodetic longitude (L).
Geodesic meridian plane - a plane passing through the normal to the surface of the earth's ellipsoid at a given point and parallel to its minor axis.
Geodetic meridian - the line along which the plane of the geodesic meridian intersects the surface of the ellipsoid.
Geodetic parallel - the line of intersection of the surface of the ellipsoid with a plane passing through a given point and perpendicular to the minor axis.

Geodetic latitude (IN)- the angle formed by the normal to the surface of the earth's ellipsoid at a given point and the plane of the equator.

Geodetic longitude (L)- dihedral angle between the plane of the geodesic meridian of a given point and the plane of the initial geodesic meridian.

Rice. 3.6. Geodetic latitude (B) and geodetic longitude (L)

3.2. DETERMINING GEOGRAPHICAL COORDINATES OF POINTS ON THE MAP

Topographic maps are printed in separate sheets, the sizes of which are set for each scale. The side frames of the sheets are meridians, and the top and bottom frames are parallels. . (Fig. 3.7). Hence, geographic coordinates can be determined by the side frames of a topographic map . On all maps, the top frame always faces north.
Geographic latitude and longitude are written in the corners of each sheet of the map. On maps of the Western Hemisphere, in the northwestern corner of the frame of each sheet, to the right of the meridian longitude value, the inscription is placed: “West of Greenwich.”
On maps of scales 1: 25,000 - 1: 200,000, the sides of the frames are divided into segments equal to 1′ (one minute, Fig. 3.7). These segments are shaded every other and separated by dots (except for a map of scale 1: 200,000) into parts of 10" (ten seconds). On each sheet, maps of scales 1: 50,000 and 1: 100,000 show, in addition, the intersection of the middle meridian and the middle parallel with digitization in degrees and minutes, and along the inner frame - outputs of minute divisions with strokes 2 - 3 mm long. This allows, if necessary, to draw parallels and meridians on a map glued from several sheets.

Rice. 3.7. Side map frames

When drawing up maps of scales 1: 500,000 and 1: 1,000,000, a cartographic grid of parallels and meridians is applied to them. Parallels are drawn at 20′ and 40″ (minutes), respectively, and meridians at 30′ and 1°.
The geographic coordinates of a point are determined from the nearest southern parallel and from the nearest western meridian, the latitude and longitude of which are known. For example, for a map of scale 1: 50,000 “ZAGORYANI”, the nearest parallel located to the south of a given point will be the parallel of 54º40′ N, and the nearest meridian located to the west of the point will be the meridian 18º00′ E. (Fig. 3.7).

Rice. 3.8. Determination of geographical coordinates

To determine the latitude of a given point you need to:

• set one leg of the measuring compass to a given point, set the other leg at the shortest distance to the nearest parallel (for our map 54º40′);
• Without changing the angle of the measuring compass, install it on the side frame with minute and second divisions, one leg should be at the southern parallel (for our map 54º40′), and the other between the 10-second points on the frame;
• count the number of minutes and seconds from the southern parallel to the second leg of the measuring compass;
• add the result to the southern latitude (for our map 54º40′).

To determine the longitude of a given point you need to:

• set one leg of the measuring compass to a given point, set the other leg at the shortest distance to the nearest meridian (for our map 18º00′);
• without changing the angle of the measuring compass, install it on the nearest horizontal frame with minute and second divisions (for our map, the lower frame), one leg should be on the nearest meridian (for our map 18º00′), and the other - between the 10-second points on horizontal frame;
• count the number of minutes and seconds from the western (left) meridian to the second leg of the measuring compass;
• add the result to the longitude of the western meridian (for our map 18º00′).

note that this method of determining the longitude of a given point for maps of scale 1:50,000 and smaller has an error due to the convergence of the meridians that limit the topographic map from the east and west. The north side of the frame will be shorter than the south. Consequently, discrepancies between longitude measurements on the north and south frames may differ by several seconds. To achieve high accuracy in the measurement results, it is necessary to determine the longitude on both the southern and northern sides of the frame, and then interpolate.
To increase the accuracy of determining geographic coordinates, you can use graphic method. To do this, it is necessary to connect the ten-second divisions of the same name closest to the point with straight lines in latitude to the south of the point and in longitude to the west of it. Then determine the sizes of the segments in latitude and longitude from the drawn lines to the position of the point and sum them accordingly with the latitude and longitude of the drawn lines.
The accuracy of determining geographic coordinates using maps of scales 1: 25,000 - 1: 200,000 is 2" and 10" respectively.

3.3. POLAR COORDINATE SYSTEM

Polar coordinates are called angular and linear quantities that determine the position of a point on the plane relative to the origin of coordinates, taken as the pole ( ABOUT), and polar axis ( OS) (Fig. 3.1).

Location of any point ( M) is determined by the position angle ( α ), measured from the polar axis to the direction to the determined point, and the distance (horizontal distance - projection of the terrain line onto the horizontal plane) from the pole to this point ( D). Polar angles are usually measured from the polar axis in a clockwise direction.

Rice. 3.9. Polar coordinate system

The following can be taken as the polar axis: the true meridian, the magnetic meridian, the vertical grid line, the direction to any landmark.

3.2. BIPOLAR COORDINATE SYSTEMS

Bipolar coordinates are called two angular or two linear quantities that determine the location of a point on a plane relative to two initial points (poles ABOUT 1 And ABOUT 2 rice. 3.10).

The position of any point is determined by two coordinates. These coordinates can be either two position angles ( α 1 And α 2 rice. 3.10), or two distances from the poles to the determined point ( D 1 And D 2 rice. 3.11).

Rice. 3.10. Determining the location of a point from two angles (α 1 and α 2 )

Rice. 3.11. Determining the location of a point by two distances

In a bipolar coordinate system, the position of the poles is known, i.e. the distance between them is known.

3.3. POINT HEIGHT

Were previously reviewed plan coordinate systems , defining the position of any point on the surface of the earth's ellipsoid, or reference ellipsoid , or on a plane. However, these plan coordinate systems do not allow one to obtain an unambiguous position of a point on the physical surface of the Earth. Geographic coordinates relate the position of a point to the surface of the reference ellipsoid, polar and bipolar coordinates relate the position of a point to a plane. And all these definitions do not in any way relate to the physical surface of the Earth, which for a geographer is more interesting than the reference ellipsoid.
Thus, plan coordinate systems do not make it possible to unambiguously determine the position of a given point. It is necessary to somehow define your position, at least with the words “above” and “below”. Just regarding what? To obtain complete information about the position of a point on the physical surface of the Earth, a third coordinate is used - height . Therefore, there is a need to consider the third coordinate system - height system .

The distance along a plumb line from a level surface to a point on the physical surface of the Earth is called height.

There are heights absolute , if they are counted from the level surface of the Earth, and relative (conditional ), if they are counted from an arbitrary level surface. Usually, the level of the ocean or open sea in a calm state is taken as the starting point for absolute heights. In Russia and Ukraine, the starting point for absolute altitude is taken to be zero of the Kronstadt footstock.

Footstock- a rail with divisions, fixed vertically on the shore so that it is possible to determine from it the position of the water surface in a calm state.
Kronstadt footstock- a line on a copper plate (board) mounted in the granite abutment of the Blue Bridge of the Obvodny Canal in Kronstadt.
The first footpole was installed during the reign of Peter 1, and from 1703 regular observations of the level of the Baltic Sea began. Soon the footstock was destroyed, and only from 1825 (and to the present) regular observations were resumed. In 1840, hydrographer M.F. Reinecke calculated the average height of the Baltic Sea level and recorded it on the granite abutment of the bridge in the form of a deep horizontal line. Since 1872, this line has been taken as the zero mark when calculating the heights of all points on the territory of the Russian state. The Kronstadt footing rod was modified several times, but the position of its main mark was kept the same during design changes, i.e. defined in 1840
After the collapse of the Soviet Union, Ukrainian surveyors did not invent their own national system of heights, and currently in Ukraine it is still used Baltic height system.

It should be noted that in every necessary case, measurements are not taken directly from the level of the Baltic Sea. There are special points on the ground, the heights of which were previously determined in the Baltic height system. These points are called benchmarks .
Absolute altitudes H can be positive (for points above the Baltic Sea level), and negative (for points below the Baltic Sea level).
The difference in absolute heights of two points is called relative height or exceeding (h):
h =H A−H IN .
The excess of one point over another can also be positive or negative. If the absolute height of a point A greater than the absolute height of the point IN, i.e. is above the point IN, then the point is exceeded A above the point IN will be positive, and vice versa, exceeding the point IN above the point A- negative.

Example. Absolute heights of points A And IN: N A = +124,78 m; N IN = +87,45 m. Find mutual excesses of points A And IN.

Solution. Exceeding point A above the point IN
h A(B) = +124,78 - (+87,45) = +37,33 m.
Exceeding point IN above the point A
h B(A) = +87,45 - (+124,78) = -37,33 m.

Example. Absolute point height A equal to N A = +124,78 m. Exceeding point WITH above the point A equals h C(A) = -165,06 m. Find the absolute height of a point WITH.

Solution. Absolute point height WITH equal to
N WITH = N A + h C(A) = +124,78 + (-165,06) = - 40,28 m.

The numerical value of the height is called the point elevation (absolute or conditional).
For example, N A = 528.752 m - absolute point elevation A; N" IN = 28.752 m - reference point elevation IN .

Rice. 3.12. Heights of points on the earth's surface

To move from conditional heights to absolute ones and vice versa, you need to know the distance from the main level surface to the conditional one.

Video
Meridians, parallels, latitudes and longitudes
Determining the position of points on the earth's surface

Questions and tasks for self-control

1. Expand the concepts: pole, equatorial plane, equator, meridian plane, meridian, parallel, degree grid, coordinates.
2. Relative to what planes on the globe (ellipsoid of revolution) are geographic coordinates determined?
3. What is the difference between astronomical geographic coordinates and geodetic ones?
4. Using a drawing, explain the concepts of “spherical latitude” and “spherical longitude”.
5. On what surface is the position of points in the astronomical coordinate system determined?
6. Using a drawing, explain the concepts of “astronomical latitude” and “astronomical longitude”.
7. On what surface are the positions of points determined in a geodetic coordinate system?
8. Using a drawing, explain the concepts of “geodetic latitude” and “geodetic longitude”.
9. Why is it necessary to connect the ten-second divisions of the same name closest to the point with straight lines to increase the accuracy of determining longitude?
10. How can you calculate the latitude of a point by determining the number of minutes and seconds from the northern frame of a topographic map?
11. What coordinates are called polar?
12. What purpose does the polar axis serve in a polar coordinate system?
13. What coordinates are called bipolar?
14. What is the essence of the direct geodetic problem?

Video lesson “Geographical latitude and geographic longitude. Geographic Coordinates" will help you get an idea of ​​geographic latitude and geographic longitude. The teacher will tell you how to correctly determine geographic coordinates.

Geographic latitude- arc length in degrees from the equator to a given point.

To determine the latitude of an object, you need to find the parallel on which this object is located.

For example, the latitude of Moscow is 55 degrees and 45 minutes north latitude, it is written like this: Moscow 55°45" N; latitude of New York - 40°43" N; Sydney - 33°52" S

Geographic longitude is determined by meridians. Longitude can be western (from the 0 meridian to the west to the 180 meridian) and eastern (from the 0 meridian to the east to the 180 meridian). Longitude values ​​are measured in degrees and minutes. Geographic longitude can have values ​​from 0 to 180 degrees.

Geographic longitude- length of the equatorial arc in degrees from the prime meridian (0 degrees) to the meridian of a given point.

The prime meridian is considered to be the Greenwich meridian (0 degrees).

Rice. 2. Determination of longitudes ()

To determine longitude, you need to find the meridian on which a given object is located.

For example, the longitude of Moscow is 37 degrees and 37 minutes east longitude, it is written like this: 37°37" east; the longitude of Mexico City is 99°08" west.

Rice. 3. Geographical latitude and geographic longitude

To accurately determine the location of an object on the surface of the Earth, you need to know its geographic latitude and geographic longitude.

Geographical coordinates- quantities that determine the position of a point on the earth’s surface using latitudes and longitudes.

For example, Moscow has the following geographic coordinates: 55°45"N and 37°37"E. The city of Beijing has the following coordinates: 39°56′ N. 116°24′ E First the latitude value is recorded.

Sometimes you need to find an object at already given coordinates; to do this, you must first guess in which hemispheres the object is located.

Homework

Paragraphs 12, 13.

1. What are geographic latitude and longitude?

Bibliography

Main

1. Basic course in geography: Textbook. for 6th grade. general education institutions / T.P. Gerasimova, N.P. Neklyukova. - 10th ed., stereotype. - M.: Bustard, 2010. - 176 p.

2. Geography. 6th grade: atlas. - 3rd ed., stereotype. - M.: Bustard, DIK, 2011. - 32 p.

3. Geography. 6th grade: atlas. - 4th ed., stereotype. - M.: Bustard, DIK, 2013. - 32 p.

4. Geography. 6th grade: cont. cards. - M.: DIK, Bustard, 2012. - 16 p.

Encyclopedias, dictionaries, reference books and statistical collections

1. Geography. Modern illustrated encyclopedia / A.P. Gorkin. - M.: Rosman-Press, 2006. - 624 p.

Literature for preparing for the State Exam and the Unified State Exam

1. Geography: initial course. Tests. Textbook manual for 6th grade students. - M.: Humanite. ed. VLADOS center, 2011. - 144 p.

2. Tests. Geography. 6-10 grades: Educational and methodological manual / A.A. Letyagin. - M.: LLC "Agency "KRPA "Olympus": "Astrel", "AST", 2001. - 284 p.

Materials on the Internet

1. Federal Institute of Pedagogical Measurements ().

2. Russian Geographical Society ().

In order to find the desired object on a map, you need to know its geographic coordinates - latitude and longitude.

Remember how in math lessons you found a point on the coordinate plane? In the same way, you can find any point on the planet using a system of parallels and meridians, or, as it is also called, a degree network.

First set the geographic latitude of the point. That is, determine how far it is from the equator. To do this, calculate the magnitude of the meridian arc from the equator to this point in degrees. Geographic latitude can vary from 0° to 90°. All points in the Northern Hemisphere have a northern latitude (abbreviated as N), and in the Southern Hemisphere they have a southern latitude (abbreviated as S).

Determination of geographical coordinates

To determine the geographic latitude of any point on the globe and map, you need to find out what parallel it is on. For example, if Moscow is located on a parallel between 50° and 60° N. latitude, then its latitude is approximately 56° N. w. All points of the same parallel have the same latitude. In order to establish the geographic longitude of a point, you need to find out how far it is from the prime (zero) meridian. It passes through the old building of the Greenwich Observatory, built in 1675 near London. This meridian was chosen conditionally as the zero meridian. That's what it's called - Greenwich. The magnitude of the parallel arc from it to a given point is measured in the same way as geographic latitude - in degrees. If you move from the prime meridian to the east, then the longitude will be eastern (abbreviated as E), and if to the west it will be western (abbreviated as W). The longitude value can range from 0° to 180°. To determine the geographic longitude of any point means to establish the longitude of the meridian on which it is located. So, Moscow is located at 38° east. Yes

Coordinates are called angular and linear quantities (numbers) that determine the position of a point on any surface or in space.

In topography, coordinate systems are used that make it possible to most simply and unambiguously determine the position of points on the earth's surface, both from the results of direct measurements on the ground and using maps. Such systems include geographic, flat rectangular, polar and bipolar coordinates.

Geographical coordinates(Fig. 1) – angular values: latitude (j) and longitude (L), which determine the position of an object on the earth’s surface relative to the origin of coordinates – the point of intersection of the prime (Greenwich) meridian with the equator. On a map, the geographic grid is indicated by a scale on all sides of the map frame. The western and eastern sides of the frame are meridians, and the northern and southern sides are parallels. In the corners of the map sheet, the geographical coordinates of the intersection points of the sides of the frame are written.

Rice. 1. System of geographical coordinates on the earth's surface

In the geographic coordinate system, the position of any point on the earth's surface relative to the origin of coordinates is determined in angular measure. In our country and in most other countries, the point of intersection of the prime (Greenwich) meridian with the equator is taken as the beginning. Being thus uniform for our entire planet, the system of geographic coordinates is convenient for solving problems of determining the relative position of objects located at significant distances from each other. Therefore, in military affairs, this system is used mainly for conducting calculations related to the use of long-range combat weapons, for example, ballistic missiles, aviation, etc.

Plane rectangular coordinates(Fig. 2) - linear quantities that determine the position of an object on a plane relative to the accepted origin of coordinates - the intersection of two mutually perpendicular lines (coordinate axes X and Y).

In topography, each 6-degree zone has its own system of rectangular coordinates. The X axis is the axial meridian of the zone, the Y axis is the equator, and the point of intersection of the axial meridian with the equator is the origin of coordinates.

Rice. 2. System of flat rectangular coordinates on maps

The plane rectangular coordinate system is zonal; it is established for each six-degree zone into which the Earth’s surface is divided when depicting it on maps in the Gaussian projection, and is intended to indicate the position of images of points of the earth’s surface on a plane (map) in this projection.

The origin of coordinates in a zone is the point of intersection of the axial meridian with the equator, relative to which the position of all other points in the zone is determined in a linear measure. The origin of the zone and its coordinate axes occupy a strictly defined position on the earth's surface. Therefore, the system of flat rectangular coordinates of each zone is connected both with the coordinate systems of all other zones, and with the system of geographical coordinates.

The use of linear quantities to determine the position of points makes the system of flat rectangular coordinates very convenient for carrying out calculations both when working on the ground and on a map. Therefore, this system is most widely used among the troops. Rectangular coordinates indicate the position of terrain points, their battle formations and targets, and with their help determine the relative position of objects within one coordinate zone or in adjacent areas of two zones.

Polar and bipolar coordinate systems are local systems. In military practice, they are used to determine the position of some points relative to others in relatively small areas of the terrain, for example, when designating targets, marking landmarks and targets, drawing up terrain diagrams, etc. These systems can be associated with systems of rectangular and geographic coordinates.

2. Determining geographic coordinates and plotting objects on a map using known coordinates

The geographic coordinates of a point located on the map are determined from the nearest parallel and meridian, the latitude and longitude of which are known.

The topographic map frame is divided into minutes, which are separated by dots into divisions of 10 seconds each. Latitudes are indicated on the sides of the frame, and longitudes are indicated on the northern and southern sides.

Rice. 3. Determining the geographic coordinates of a point on the map (point A) and plotting the point on the map according to geographic coordinates (point B)

Using the minute frame of the map you can:

1 . Determine the geographic coordinates of any point on the map.

For example, the coordinates of point A (Fig. 3). To do this, you need to use a measuring compass to measure the shortest distance from point A to the southern frame of the map, then attach the meter to the western frame and determine the number of minutes and seconds in the measured segment, add the resulting (measured) value of minutes and seconds (0"27") with the latitude of the southwest corner of the frame - 54°30".

Latitude points on the map will be equal to: 54°30"+0"27" = 54°30"27".

Longitude is defined similarly.

Using a measuring compass, measure the shortest distance from point A to the western frame of the map, apply the measuring compass to the southern frame, determine the number of minutes and seconds in the measured segment (2"35"), add the resulting (measured) value to the longitude of the southwestern corner frames - 45°00".

Longitude points on the map will be equal to: 45°00"+2"35" = 45°02"35"

2. Plot any point on the map according to the given geographical coordinates.

For example, point B latitude: 54°31 "08", longitude 45°01 "41".

To plot a point in longitude on a map, it is necessary to draw the true meridian through this point, for which you connect the same number of minutes along the northern and southern frames; To plot a point in latitude on a map, it is necessary to draw a parallel through this point, for which you connect the same number of minutes along the western and eastern frames. The intersection of two lines will determine the location of point B.

3. Rectangular coordinate grid on topographic maps and its digitization. Additional grid at the junction of coordinate zones

The coordinate grid on the map is a grid of squares formed by lines parallel to the coordinate axes of the zone. Grid lines are drawn through an integer number of kilometers. Therefore, the coordinate grid is also called the kilometer grid, and its lines are kilometer.

On a 1:25000 map, the lines forming the coordinate grid are drawn through 4 cm, that is, through 1 km on the ground, and on maps 1:50000-1:200000 through 2 cm (1.2 and 4 km on the ground, respectively). On a 1:500000 map, only the outputs of the coordinate grid lines are plotted on the inner frame of each sheet every 2 cm (10 km on the ground). If necessary, coordinate lines can be drawn on the map along these outputs.

On topographic maps, the values ​​of the abscissa and ordinate of coordinate lines (Fig. 2) are signed at the exits of the lines outside the inner frame of the sheet and in nine places on each sheet of the map. The full values ​​of the abscissa and ordinate in kilometers are written near the coordinate lines closest to the corners of the map frame and near the intersection of the coordinate lines closest to the northwestern corner. The remaining coordinate lines are abbreviated with two numbers (tens and units of kilometers). The labels near the horizontal grid lines correspond to the distances from the ordinate axis in kilometers.

Labels near the vertical lines indicate the zone number (one or two first digits) and the distance in kilometers (always three digits) from the origin of coordinates, conventionally moved west of the zone’s axial meridian by 500 km. For example, the signature 6740 means: 6 - zone number, 740 - distance from the conventional origin in kilometers.

On the outer frame there are outputs of coordinate lines ( additional mesh) coordinate system of the adjacent zone.

4. Determination of rectangular coordinates of points. Drawing points on a map by their coordinates

Using a coordinate grid using a compass (ruler), you can:

1. Determine the rectangular coordinates of a point on the map.

For example, points B (Fig. 2).

To do this you need:

• write down X - digitization of the bottom kilometer line of the square in which point B is located, i.e. 6657 km;
• measure the perpendicular distance from the bottom kilometer line of the square to point B and, using the linear scale of the map, determine the size of this segment in meters;
• add the measured value of 575 m with the digitization value of the lower kilometer line of the square: X=6657000+575=6657575 m.

The Y ordinate is determined in the same way:

• write down the Y value - digitization of the left vertical line of the square, i.e. 7363;
• measure the perpendicular distance from this line to point B, i.e. 335 m;
• add the measured distance to the Y digitization value of the left vertical line of the square: Y=7363000+335=7363335 m.

2. Place the target on the map at the given coordinates.

For example, point G at coordinates: X=6658725 Y=7362360.

To do this you need:

• find the square in which point G is located according to the value of whole kilometers, i.e. 5862;
• set aside from the lower left corner of the square a segment on the map scale equal to the difference between the abscissa of the target and the bottom side of the square - 725 m;
• From the obtained point, along the perpendicular to the right, plot a segment equal to the difference between the ordinates of the target and the left side of the square, i.e. 360 m.

Rice. 2. Determining the rectangular coordinates of a point on the map (point B) and plotting the point on the map using rectangular coordinates (point D)

5. Accuracy of determining coordinates on maps of various scales

The accuracy of determining geographic coordinates using 1:25000-1:200000 maps is about 2 and 10"" respectively.

The accuracy of determining the rectangular coordinates of points from a map is limited not only by its scale, but also by the magnitude of errors allowed when shooting or drawing up a map and plotting various points and terrain objects on it

Most accurately (with an error not exceeding 0.2 mm) geodetic points and are plotted on the map. objects that stand out most sharply in the area and are visible from a distance, having the significance of landmarks (individual bell towers, factory chimneys, tower-type buildings). Therefore, the coordinates of such points can be determined with approximately the same accuracy with which they are plotted on the map, i.e. for a map of scale 1:25000 - with an accuracy of 5-7 m, for a map of scale 1:50000 - with an accuracy of 10- 15 m, for a map of scale 1:100000 - with an accuracy of 20-30 m.

The remaining landmarks and contour points are plotted on the map, and, therefore, determined from it with an error of up to 0.5 mm, and points related to contours that are not clearly defined on the ground (for example, the contour of a swamp), with an error of up to 1 mm.

6. Determining the position of objects (points) in polar and bipolar coordinate systems, plotting objects on a map by direction and distance, by two angles or by two distances

System flat polar coordinates(Fig. 3, a) consists of point O - the origin, or poles, and the initial direction of the OR, called polar axis.

Rice. 3. a – polar coordinates; b – bipolar coordinates

The position of point M on the ground or on the map in this system is determined by two coordinates: the position angle θ, which is measured clockwise from the polar axis to the direction to the determined point M (from 0 to 360°), and the distance OM=D.

Depending on the problem being solved, the pole is taken to be an observation point, firing position, starting point of movement, etc., and the polar axis is the geographic (true) meridian, magnetic meridian (direction of the magnetic compass needle), or the direction to some landmark .

These coordinates can be either two position angles that determine the directions from points A and B to the desired point M, or the distances D1=AM and D2=BM to it. The position angles in this case, as shown in Fig. 1, b, are measured at points A and B or from the direction of the basis (i.e. angle A = BAM and angle B = ABM) or from any other directions passing through points A and B and taken as the initial ones. For example, in the second case, the location of point M is determined by the position angles θ1 and θ2, measured from the direction of the magnetic meridians. System flat bipolar (two-pole) coordinates(Fig. 3, b) consists of two poles A and B and a common axis AB, called the basis or base of the notch. The position of any point M relative to two data on the map (terrain) of points A and B is determined by the coordinates that are measured on the map or on the terrain.

Drawing a detected object on a map

This is one of the most important points in detecting an object. The accuracy of determining its coordinates depends on how accurately the object (target) is plotted on the map.

Having discovered an object (target), you must first accurately determine by various signs what has been detected. Then, without stopping observing the object and without detecting yourself, put the object on the map. There are several ways to plot an object on a map.

Visually: A feature is plotted on the map if it is near a known landmark.

By direction and distance: to do this, you need to orient the map, find the point of your standing on it, indicate on the map the direction to the detected object and draw a line to the object from the point of your standing, then determine the distance to the object by measuring this distance on the map and comparing it with the scale of the map.

Rice. 4. Drawing the target on the map with a straight line from two points.

If it is graphically impossible to solve the problem in this way (the enemy is in the way, poor visibility, etc.), then you need to accurately measure the azimuth to the object, then translate it into a directional angle and draw on the map from the standing point the direction at which to plot the distance to the object.

To obtain a directional angle, you need to add the magnetic declination of a given map to the magnetic azimuth (direction correction).

Straight serif. In this way, an object is placed on a map of 2-3 points from which it can be observed. To do this, from each selected point, the direction to the object is drawn on an oriented map, then the intersection of straight lines determines the location of the object.

7. Methods of target designation on the map: in graphic coordinates, flat rectangular coordinates (full and abbreviated), by kilometer grid squares (up to a whole square, up to 1/4, up to 1/9 square), from a landmark, from a conventional line, in azimuth and target range, in the bipolar coordinate system

The ability to quickly and correctly indicate targets, landmarks and other objects on the ground is important for controlling units and fire in battle or for organizing battle.

Targeting in geographical coordinates used very rarely and only in cases where targets are located at a considerable distance from a given point on the map, expressed in tens or hundreds of kilometers. In this case, geographic coordinates are determined from the map, as described in question No. 2 of this lesson.

The location of the target (object) is indicated by latitude and longitude, for example, height 245.2 (40° 8" 40" N, 65° 31" 00" E). On the eastern (western), northern (southern) sides of the topographic frame, marks of the target position in latitude and longitude are applied with a compass. From these marks, perpendiculars are lowered into the depth of the topographic map sheet until they intersect (commander’s rulers and standard sheets of paper are applied). The point of intersection of the perpendiculars is the position of the target on the map.

For approximate target designation by rectangular coordinates It is enough to indicate on the map the grid square in which the object is located. The square is always indicated by the numbers of the kilometer lines, the intersection of which forms the southwest (lower left) corner. When indicating the square of the map, the following rule is followed: first they call two numbers signed at the horizontal line (on the western side), that is, the “X” coordinate, and then two numbers at the vertical line (the southern side of the sheet), that is, the “Y” coordinate. In this case, “X” and “Y” are not said. For example, enemy tanks were detected. When transmitting a report by radiotelephone, the square number is pronounced: "eighty eight zero two."

If the position of a point (object) needs to be determined more accurately, then full or abbreviated coordinates are used.

Work with full coordinates. For example, you need to determine the coordinates of a road sign in square 8803 on a map at a scale of 1:50000. First, determine the distance from the bottom horizontal side of the square to the road sign (for example, 600 m on the ground). In the same way, measure the distance from the left vertical side of the square (for example, 500 m). Now, by digitizing kilometer lines, we determine the full coordinates of the object. The horizontal line has the signature 5988 (X), adding the distance from this line to the road sign, we get: X = 5988600. We define the vertical line in the same way and get 2403500. The full coordinates of the road sign are as follows: X=5988600 m, Y=2403500 m.

Abbreviated coordinates respectively will be equal: X=88600 m, Y=03500 m.

If it is necessary to clarify the position of a target in a square, then target designation is used in an alphabetic or digital way inside the square of a kilometer grid.

During target designation literal way inside the square of the kilometer grid, the square is conditionally divided into 4 parts, each part is assigned a capital letter of the Russian alphabet.

Second way - digital way target designation inside the square kilometer grid (target designation by snail ). This method got its name from the arrangement of conventional digital squares inside the square of the kilometer grid. They are arranged as if in a spiral, with the square divided into 9 parts.

When designating targets in these cases, they name the square in which the target is located, and add a letter or number that specifies the position of the target inside the square. For example, height 51.8 (5863-A) or high-voltage support (5762-2) (see Fig. 2).

Target designation from a landmark is the simplest and most common method of target designation. With this method of target designation, the landmark closest to the target is first named, then the angle between the direction to the landmark and the direction to the target in protractor divisions (measured with binoculars) and the distance to the target in meters. For example: “Landmark two, forty to the right, further two hundred, near a separate bush there is a machine gun.”

Target designation from the conditional line usually used in motion on combat vehicles. With this method, two points are selected on the map in the direction of action and connected by a straight line, relative to which target designation will be carried out. This line is denoted by letters, divided into centimeter divisions and numbered starting from zero. This construction is done on the maps of both transmitting and receiving target designation.

Target designation from a conventional line is usually used in movement on combat vehicles. With this method, two points are selected on the map in the direction of action and connected by a straight line (Fig. 5), relative to which target designation will be carried out. This line is denoted by letters, divided into centimeter divisions and numbered starting from zero.

Rice. 5. Target designation from the conditional line

This construction is done on the maps of both transmitting and receiving target designation.

The position of the target relative to the conditional line is determined by two coordinates: a segment from the starting point to the base of the perpendicular lowered from the target location point to the conditional line, and a perpendicular segment from the conditional line to the target.

When designating targets, the conventional name of the line is called, then the number of centimeters and millimeters contained in the first segment, and, finally, the direction (left or right) and the length of the second segment. For example: “Straight AC, five, seven; to the right zero, six - NP.”

Target designation from a conventional line can be given by indicating the direction to the target at an angle from the conventional line and the distance to the target, for example: “Straight AC, right 3-40, one thousand two hundred – machine gun.”

Target designation in azimuth and range to the target. The azimuth of the direction to the target is determined using a compass in degrees, and the distance to it is determined using an observation device or by eye in meters. For example: “Azimuth thirty-five, range six hundred—a tank in a trench.” This method is most often used in areas where there are few landmarks.

8. Problem solving

Determining the coordinates of terrain points (objects) and target designation on the map is practiced practically on training maps using previously prepared points (marked objects).

Each student determines geographic and rectangular coordinates (maps objects according to known coordinates).

Methods of target designation on the map are worked out: in flat rectangular coordinates (full and abbreviated), by squares of a kilometer grid (up to a whole square, up to 1/4, up to 1/9 of a square), from a landmark, along the azimuth and range of the target.

Since the time of man's access to the seas, the need to determine longitude and latitude has been a vital human skill. Epochs changed, and man became able to determine the cardinal directions in any weather. New methods of determining one's position were required.

The captain of a Spanish galleon in the eighteenth century knew exactly where the ship was thanks to the position of the stars in the night sky. A 19th-century traveler could detect deviations from the established route in the forest by natural clues.

Now it’s the twenty-first century and many have lost the knowledge gained from geography lessons. Android or iPhone smartphones can serve as a tool, but they can never replace the knowledge and ability to determine your location.

What is latitude and longitude in geography

Determination of geographical coordinates

Apps that users install on iPhone read location coordinates to provide services or data based on where a person is located. After all, if a subscriber is in Russia, then there is no reason for him to read sites in English. Everything happens in the background.

While the average user will never deal with GPS coordinates, knowing how to obtain and read them can be valuable. In some cases, they can save lives when there is no card nearby.

In any geographical system there are two indicators: latitude and longitude. Geodata from a smartphone shows exactly where the user is located relative to the equator.

How to determine the latitude and longitude of your location

Let's consider two options for determining geographic coordinates:

1. Via Android The simplest is the Google Maps application, perhaps the most comprehensive collection of geographic maps in one application. After launching the Google maps application, the location on the road map will be pinpointed so that the user can get the best possible understanding of the surrounding area. The app also offers an extensive list of features, including real-time GPS navigation, traffic conditions and transit information, as well as detailed information about nearby places, including popular food and recreation spots, photos and reviews.
2. Via iPhone You won't need any third party app to view latitude and longitude data. The location is determined only with the maps application. To find out the current coordinates, just launch “maps”. Tap the arrow in the upper right corner of the screen, then tap the blue dot - this indicates the location of the phone and the user. Next, we swipe up the screen, and now the user can see the GPS coordinates. Unfortunately, there is no way to copy these coordinates, but you can get similar data.

To copy them you will need another Compass application. It's already installed on your iPhone and you can use it right away.

To view latitude, longitude, and altitude coordinates in the Compass app, simply launch and find the data at the bottom.

Determining the geographical coordinates of Moscow

For this:

1. Open maps of the Yandex search engine.
2. In the address bar, enter the name of our capital “Moscow”.
3. The city center (Kremlin) opens and under the name of the country we find the numbers 55.753215, 37.622504 - these are the coordinates, that is, 55.753215 north latitude and 37.622504 east longitude.

Throughout the world, GPS coordinates are determined by latitude and longitude according to the wgs-84 coordinate system.

In all situations, the latitude coordinate is a point relative to the equator, and the longitude coordinate is a point relative to the meridian of the British Royal Observatory at Greenwich, in the UK. This determines two important parameters of online geography.

Finding the latitude and longitude of St. Petersburg

To consolidate the skill, we will repeat the same algorithm of actions, but for the Northern capital:

1. Open Yandex cards.
2. We write down the name of the northern capital “St. Petersburg”.
3. The result of the request will be a panorama of Palace Square and the required coordinates 59.939095, 30.315868.

Coordinates of Russian cities and world capitals in the table

Cities of Russia	Latitude	Longitude
Moscow	55.753215	37.622504
Saint Petersburg	59.939095	30.315868
Novosibirsk	55.030199	82.920430
Ekaterinburg	56.838011	60.597465
Vladivostok	43.115536	131.885485
Yakutsk	62.028103	129.732663
Chelyabinsk	55.159897	61.402554
Kharkiv	49.992167	36.231202
Smolensk	54.782640	32.045134
Omsk	54.989342	73.368212
Krasnoyarsk	56.010563	92.852572
Rostov	57.185866	39.414526
Bryansk	53.243325	34.363731
Sochi	43.585525	39.723062
Ivanovo	57.000348	40.973921

Capitals of world states	Latitude	Longitude
Tokyo	35.682272	139.753137
Brasilia	-15.802118	-47.889062
Kyiv	50.450458	30.523460
Washington	38.891896	-77.033788
Cairo	30.065993	31.266061
Beijing	39.901698	116.391433
Delhi	28.632909	77.220026
Minsk	53.902496	27.561481
Berlin	52.519405	13.406323
Wellington	-41.297278	174.776069

Reading GPS data or where negative numbers come from

The object's geographic positioning system has changed several times. Now, thanks to it, you can quite accurately determine the distance to the desired object and find out the coordinates.

The ability to show location is a vital necessity during search operations of rescue services. There are different situations with travelers, tourists or extreme sports enthusiasts. It is then that high accuracy is important, when a person is on the verge of life, and minutes count.

Now, dear reader, having such knowledge, you may have questions. There are many of them, but even from the table one of the most interesting emerges - why is the number negative? Let's figure it out.

GPS, when translated into Russian, sounds like this – “global positioning system”. We remember that the distance to the desired geographical object (city, village, village, etc.) is measured according to two landmarks on the globe: the equator and the observatory in London.

At school they talked about latitude and longitude, but in Yandex maps they are replaced with the left and right parts of the code. If the navigator shows positive values, then you are going in a northerly direction. Otherwise, the numbers become negative, indicating southern latitude.

The same goes for longitude. Positive values ​​are eastern longitude, and negative values ​​are western longitude.

For example, the coordinates of the Lenin Library in Moscow: 55°45’08.1″N 37°36’36.9″E. It reads like this: “55 degrees 45 minutes and 08.1 seconds north latitude and 37 degrees 36 minutes and 36.9 seconds east longitude” (data from Google maps).