What is latitude and longitude? Geographic latitude and geographic longitude. Geographical coordinates

Since the time of man's entry into the seas, the need to determine longitude and latitude has been a vital human skill. Epochs changed, and a person became able to determine the cardinal directions in any weather. More and more 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 due to the position of the stars in the night sky. A 19th-century traveler could determine a deviation from an established route in the forest from natural clues.

Now it's the twenty-first century and many have lost the knowledge gained in geography lessons. Smartphones based on Android or iPhone can serve as a tool, but they will never replace the knowledge and ability to determine your location.

What is latitude and longitude in geography

Determination of geographical coordinates

Applications that users install on iPhones read location coordinates to provide services or data based on where the person is located. After all, if the subscriber is in Russia, then he has no reason to read sites in English. Everything happens in the background.

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

In any geographic 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

Consider two options for determining geographic coordinates:

Via Android the simplest is the Google Maps application, perhaps the most complete collection of geographic maps in one application. After launching the Google maps application, the location on the road map will be accurately determined, so that the user can get the best idea of the surrounding area. The app also offers an extensive list of features, including real-time GPS navigation, traffic status, and transit information, as well as detailed information about nearby places, including popular food and holiday spots, photos, and reviews.
Through iPhone you don'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 run the "maps". Touch the arrow in the upper right corner of the screen, then touch the blue dot - this is the designation of 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 such data.

You will need another Compass application to copy them. It is already installed on the iPhone, you can immediately use it.

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

Determine the geographical coordinates of Moscow

For this:

We open the cards of the yandex search engine.
Enter the name of our capital "Moscow" in the address bar.
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.

Worldwide GPS coordinates are defined by latitude and longitude according to the wgs-84 coordinate system.

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

Finding the latitude and longitude of St. Petersburg

To consolidate the skill, let's repeat the same algorithm of actions, but for the Northern capital:

We open "Yandex" maps.
We prescribe the name of the northern capital "St. Petersburg".
The result of the request will be a panorama of the Palace Square and the desired 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
St. Petersburg	59.939095	30.315868
Novosibirsk	55.030199	82.920430
Yekaterinburg	56.838011	60.597465
Vladivostok	43.115536	131.885485
Yakutsk	62.028103	129.732663
Chelyabinsk	55.159897	61.402554
Kharkov	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 accurately determine the distance to the desired object and find out the coordinates.

The ability to show the location is a vital necessity in the search activities of the rescue services. Different situations happen with travelers, tourists or extreme sportsmen. 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 arises - why is the number negative? Let's figure it out.

GPS when translated into Russian sounds like this - "global position system". Remember that the distance to the desired geographical object (city, village, village, and so on) is calculated 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 by the left and right parts of the code. If the navigator has positive values, then you are heading north. Otherwise, the numbers become negative, which indicates the southern latitude.

Likewise with longitude. Positive values are east longitude and negative values are west longitude.

For example, the coordinates of the Lenin Library in Moscow are: 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).

In Chapter 1, it was noted that the Earth has the shape of a spheroid, that is, an oblate ball. Since the terrestrial 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 an 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) is the pole opposite to the north.
If we mentally cut the globe with a plane passing through the axis (parallel to the axis) of the Earth's rotation, we get an imaginary plane, which is called meridian plane . The line of intersection of this plane with the earth's surface is called geographic (or true) meridian .
The plane perpendicular to the earth's axis and passing through the center of the earth is called equatorial plane , and the line of intersection of this plane with the earth's surface - equator .
If you mentally cross the globe with planes parallel to the equator, then circles are obtained on the surface of the Earth, which are called parallels .
Parallels and meridians plotted on globes and maps make up degree grid (Fig. 3.1). The degree grid makes it possible to determine the position of any point on the earth's surface.
For the initial meridian in the preparation of topographic maps taken 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 Hirstmonceau Castle 102.5 meters (5.31 seconds) east of the Greenwich Astronomical Meridian. The 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 by 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 a point relative to the earth's equator and one of the meridians, taken as the initial one. Geographic coordinates may be derived from astronomical observations or geodetic measurements. In the first case they are called astronomical , in the second - geodetic . For astronomical observations, the projection of points onto the surface is carried out by plumb lines, for geodetic measurements - by normals, therefore the values of astronomical and geodetic geographical coordinates are somewhat different. To create small-scale geographical 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 - angular value that determines the position of a point on Earth in the direction from the equator (0º) to the North Pole (+90º) or 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 - 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 called the angular quantities (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 initial 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) is the angle between the zero meridian plane and the meridian plane of the given point (the plane passes through the given point and the axis of rotation).

Rice. 3.4. Geographic spherical coordinate system

In the practice of topography, a sphere with a radius R = 6371 is used km, whose surface 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, which 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) called 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 axis of rotation of the Earth.
astronomical meridian - line of intersection of the surface of the geoid with the plane of the astronomical meridian.

Astronomical longitude (λ) called 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

AT geodetic geographic coordinate system for the surface on which the positions of the points are found, the surface is taken reference -ellipsoid . The position of a point on the surface of the reference ellipsoid is determined by two angular quantities - the geodetic latitude (AT) and geodetic longitude (L).
Plane of the geodesic meridian - 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 an ellipsoid by a plane passing through a given point and perpendicular to the minor axis.

Geodetic latitude (AT)- 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 the given point and the plane of the initial geodesic meridian.

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

3.2. DETERMINATION OF 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 the meridians, and the upper and lower frames are the parallels. . (Fig. 3.7). Hence, geographic coordinates can be determined by the side frames of the topographic map . On all maps, the top frame always faces north.
Geographic latitude and longitude are signed 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 longitude of the meridian, 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 through one and divided by dots (except for the 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 frames of the card

When compiling 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, respectively, through 20′ and 40 "(minutes), and meridians - through 30" and 1 °.
The geographical 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 with a scale of 1: 50,000 "ZAGORYANI", the nearest parallel located to the south of a given point will be the parallel 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 must:

set one leg of the measuring compass to a given point, set the other leg along the shortest distance to the nearest parallel (for our map 54º40 ′);
without changing the solution of the measuring compass, install it on the side frame with minute and second divisions, one leg should be on the south 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 south parallel to the second leg of the measuring compass;
add the result obtained to the south latitude (for our map 54º40 ′).

To determine the longitude of a given point, you must:

set one leg of the measuring compass to a given point, set the other leg along the shortest distance to the nearest meridian (for our map 18º00 ′);
without changing the solution of the measuring compass, set it to 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 at a scale of 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 side. Therefore, the discrepancies between the measurements of longitude on the northern and southern frames may differ by several seconds. To achieve high accuracy in the measurement results, it is necessary to determine the longitude on both the south and north sides of the frame, and then interpolate.
To improve the accuracy of determining geographic coordinates, you can use graphic method. To do this, it is necessary to connect with straight lines the nearest ten-second divisions of the same name to the point in latitude to the south of the point and in longitude to the west of it. Then determine the dimensions of the segments in latitude and longitude from the drawn lines to the position of the point and summarize them, respectively, with the latitude and longitude of the drawn lines.
The accuracy of determining geographical coordinates on maps of scales 1: 25,000 - 1: 200,000 is 2" and 10", respectively.

3.3. POLAR COORDINATE SYSTEM

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

The 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 - the projection of the terrain line on 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

For the polar axis can be taken: the true meridian, the magnetic meridian, the vertical line of the grid, the direction to any landmark.

3.2. BIPOLAR COORDINATE SYSTEMS

Bipolar coordinates call two angular or two linear quantities that determine the location of a point on a plane relative to two starting points (poles O 1 and O 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 at 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

Previously reviewed plan coordinate systems , defining the position of any point on the surface of the earth's ellipsoid, or the reference ellipsoid , or on the plane. However, these planned coordinate systems do not allow obtaining an unambiguous position of a point on the physical surface of the Earth. Geographical coordinates refer the position of the point to the surface of the reference ellipsoid, polar and bipolar coordinates refer the position of the point to the plane. And all these definitions have nothing to do with the physical surface of the Earth, which is more interesting for a geographer than a reference ellipsoid.
Thus, the planned 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”, “below”. Just about what? To obtain complete information about the position of a point on the physical surface of the Earth, the third coordinate is used - height . Therefore, it becomes necessary to consider the third coordinate system - height system .

The distance along a plumb line from the 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 the open sea in a calm state is taken as the origin of absolute heights. In Russia and Ukraine, the absolute heights are taken as the origin zero of the Kronstadt footstock.

Footstock- a rail with divisions, fixed vertically on the shore so that it is possible to determine the position of the water surface in a calm state by it.
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 footstock was installed during the reign of Peter the Great, and since 1703 regular observations of the level of the Baltic Sea began. Soon the footstock was destroyed, and only from 1825 (and up to the present time) regular observations were resumed. In 1840, hydrographer M.F. Reinecke calculated the average height of the Baltic Sea and recorded it on the granite abutment of the bridge in the form of a deep horizontal line. Since 1872, this feature has been taken as a zero mark when calculating the heights of all points on the territory of the Russian state. The Kronstadt footstock was repeatedly modified, however, the position of its main mark was kept the same during design changes, i.e. determined 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 system of heights. These points are called benchmarks .
Absolute heights H can be positive (for points above the Baltic Sea level) and negative (for points below the Baltic Sea level).
The difference between the absolute heights of two points is called relative height or excess (h):
h = H BUT-H AT .
The excess of one point over another can also be positive and negative. If the absolute height of the point BUT greater than the absolute height of the point AT, i.e. is above the point AT, then the excess of the point BUT over the dot AT will be positive, and vice versa, exceeding the point AT over the dot BUT- negative.

Example. Absolute heights of points BUT and AT: H BUT = +124,78 m; H AT = +87,45 m. Find Mutual Exceedances of Points BUT and AT.

Decision. Exceeding point BUT over the dot AT
h A(B) = +124,78 - (+87,45) = +37,33 m.
Exceeding point AT over the dot BUT
h B(A) = +87,45 - (+124,78) = -37,33 m.

Example. Point absolute height BUT is equal to H BUT = +124,78 m. Exceeding point With over the dot BUT equals h C(A) = -165,06 m. Find the absolute height of a point With.

Decision. Point absolute height With is equal to
H With = H BUT + h C(A) = +124,78 + (-165,06) = - 40,28 m.

The numerical value of the height is called the elevation of the point (absolute or conditional).
for example, H BUT = 528.752 m - absolute mark of the point BUT; H" AT \u003d 28.752 m - conditional elevation of the point AT .

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

To move from conditional to absolute heights and vice versa, it is necessary 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

Expand the concepts: pole, equatorial plane, equator, meridian plane, meridian, parallel, degree grid, coordinates.
Relative to what planes on the globe (ellipsoid of revolution) are geographic coordinates determined?
What is the difference between astronomical geographic coordinates and geodetic coordinates?
Using the drawing, expand the concepts of "spherical latitude" and "spherical longitude".
On what surface is the position of points in the astronomical coordinate system determined?
Using the drawing, expand the concepts of "astronomical latitude" and "astronomical longitude".
On what surface is the position of points in the geodetic coordinate system determined?
Using the drawing, expand the concepts of "geodesic latitude" and "geodesic longitude".
Why, in order to improve the accuracy of determining longitude, is it necessary to connect the nearest ten-second divisions of the same name to the point with straight lines?
How can you calculate the latitude of a point if you determine the number of minutes and seconds from the northern frame of a topographic map?
What are the polar coordinates?
What is the purpose of the polar axis in a polar coordinate system?
What coordinates are called bipolar?
What is the essence of the direct geodetic problem?

The ability to “read” a map is a very interesting and useful activity. Today, when with the help of innovative technologies it is possible to virtually visit any corner of the world, the possession of such skills is very rare. Geographic latitude is studied in the school curriculum, but without constant practice it is impossible to consolidate the theoretical knowledge gained in the general education course. Cartographic skills develop not only imagination, but also are a necessary basis for many complex disciplines. Those wishing to acquire the profession of navigator, surveyor, architect and military simply need to know the basic principles of working with a map and plan. Determination of geographic latitude is a mandatory skill that a real travel lover and just an educated person should have.

the globe

Before moving on to the magnitude algorithm, it is necessary to become more familiar with the globe and map. Because it is on them that you will have to train your skills. A globe is a miniature model of our Earth, which depicts its surface. M. Behaim, the creator of the famous "Earth Apple" in the 15th century, is considered the author of the very first model. The history of the development of cartographic knowledge has information about other famous globes.

Multitouch. This interactive model is a modern invention that allows you to "visit" anywhere in the world without spending a lot of time and effort!
Heavenly. This globe shows the location of cosmic bodies - mirrored. After all, when we admire the beautiful night sky, we are “inside” the dome, and we are forced to look at this globe from the outside!
One of the collectors - Sh.Missine - has a globe carved from an ostrich egg. This is one of the very first maps of this continent.

On the globe, you can accurately determine the geographical latitude, because it has the least distortion. But for greater reliability, it is necessary to use a special flexible ruler.

Cards

The globe is not very convenient to take with you on a trip, besides, it becomes more useless the smaller it is. And over time, people began to use the card. It, of course, has more errors, since it is very difficult to accurately depict the convex shape of the Earth on a piece of paper, but it is more convenient and easy to use. Maps have several classifications, but we will focus on their difference in scale, as we are talking about acquiring the skills of determining coordinates.

Large scale. This is the name of drawings with a scale (M) from 1:100,000 to 1:10,000. If the map has M 1:5,000, and larger, then it is already called a plan.
Medium scale. This is the name of the drawings of the Earth's surface, which have MM from 1:1,000,000 to 1:200,000.
Small scale. These are drawings with M 1:1,000,000 or less, for example - MM 1:2,000,000, 1:50,000,000, etc.

On a large-scale map, the geographic latitude is most easily determined, since the image is plotted on it in more detail. This is due to the fact that the grid lines are located at a small distance.

Geographic latitude

This is the name of the angle between the zero parallel and the plumb line at a given point. The resulting value can only be within 90 degrees. It is important to remember: the equator divides our Earth into the south, and therefore the latitude of all points on the Earth that are located above will be north, and below - south. How to determine the geographic latitude of an object? It is necessary to carefully look at which parallel it is located. If it is not indicated, then it is necessary to calculate what is the distance between adjacent lines and determine the degree of the desired parallel.

Geographic longitude

This is the meridian of a particular point on the Earth and which has the name Greenwich Mean. All objects to the right of it are considered eastern, and to the left - western. Longitude shows on which meridian the desired object is located. If the point to be determined is not located on the meridian indicated on the map, then we proceed in the same way as in the case of determining the desired parallel.

Geographic address

It is present in every object on our Earth. The intersection of parallels and meridians on a map or globe is called a grid (degree grid), along which the coordinates of the desired point are determined. Knowing them, you can not only determine the place where the object is located, but also correlate its position with others. Having information about the geographical address of a particular point, it is possible to correctly plot the boundaries of territories on contour maps.

Five main latitudes

On any map, the main parallels are highlighted, which facilitate the determination of coordinates. The territories that are between these main latitude lines, depending on location, may be included in the following areas: the Arctic, the tropics, equatorial and temperate.

The equator is the longest parallel. The length of lines located above or below it becomes shorter towards the poles. What is the geographic latitude of the equator? It is equal to 0 degrees, as it is considered the starting point of the parallels to the north and south. The territories that are located from the equator to the tropics are called the equatorial regions.

The northern tropic is the main parallel, which is always marked on world maps of the Earth. It is located 23 degrees 26 minutes and 16 seconds north of the equator. Another name for this parallel is the Tropic of Cancer.
The Southern Tropic is a parallel that is located 23 degrees 26 minutes and 16 seconds south of the equator. It also has a second name - the Tropic of Capricorn. The territories that are located between these lines and the equator are called tropical regions.
located 66 degrees 33 minutes and 44 seconds above the equator. It limits the territory beyond which the time of night increases, closer to the pole it reaches 40 days.

South polar circle. Its geographic latitude is 66 degrees 33 minutes and 44 seconds. This parallel is also the boundary beyond which phenomena such as polar night and day begin. The territories that are located between these lines and the tropics are called temperate regions, and beyond them - polar.

Latitude- the angle between the local direction of the zenith and the plane of the equator, counted from 0 to 90 in both directions from the equator. The geographical latitude of points lying in the northern hemisphere (northern latitude) is considered to be positive, the latitude of points in the southern hemisphere is negative. In addition, it is customary to talk about latitudes that are larger in absolute value - as high, and about those close to zero (that is, to the equator) - as about low.

Longitude

Longitude- the angle between the plane of the meridian passing through the given point, and the plane of the initial zero meridian, from which the longitude is calculated. Now on Earth, the zero meridian is the one that passes through the old observatory in the city of Greenwich, and therefore it is called the Greenwich meridian. Longitudes from 0 to 180 ° east of the zero meridian are called eastern, to the west - western. Eastern longitudes are considered to be positive, western - negative. It should be emphasized that, in contrast to latitude, for a system of longitudes, the choice of the reference point (zero meridian) is arbitrary and depends only on the agreement. So, in addition to Greenwich, the meridians of the observatories of Paris, Cadiz, Pulkovo (on the territory of the Russian Empire), etc. were previously chosen as zero.

Height

To fully determine the position of a point in three-dimensional space, a third coordinate is needed - height. The distance to the center of the planet is not used in geography: it is convenient only when describing very deep regions of the planet or, on the contrary, when calculating orbits in space.

Within the geographic envelope, it is usually used height above sea level, counted from the level of the "smoothed" surface - the geoid. Such a system of three coordinates turns out to be orthogonal, which simplifies a number of calculations. Altitude above sea level is also convenient in that it is related to atmospheric pressure.

The distance from the earth's surface (up or down) is often used to describe a location, however not serves coordinate due to surface roughness.

Latitude and longitude - terms and definitions

The earth's sphere is divided by an imaginary horizontal line into two equal parts of the world - the northern and southern hemispheres - into the positive and negative poles, respectively. This is how the definitions of northern and southern latitudes are introduced. Latitude is represented as circles parallel to the equator, called parallels. The equator itself with a value of 0 degrees is the starting point for measurements. The closer the parallel is to the upper or lower pole, the smaller its diameter and the higher or lower the angular degree. For example, the city of Moscow is located at 55 degrees north latitude, which determines the location of the capital as approximately equidistant from both the equator and the north pole.

Meridian - the so-called longitude, represented as a vertical arc strictly perpendicular to the circles of the parallel. The sphere is divided into 360 meridians. The starting point is the zero meridian (0 degrees), the arcs of which pass vertically through the points of the north and south poles and spread in east and west directions. This defines the angle of longitude from 0 to 180 degrees, calculated from the center to the extreme points to the east or south.

Unlike latitude, which is based on the equatorial line, any meridian can be zero. But for convenience, namely the convenience of counting time, the Greenwich meridian was determined.

Geographic coordinates - place and time

Latitude and longitude allow you to assign to a particular place on the planet an exact geographical address, measured in degrees. Degrees, in turn, are divided into smaller units, such as minutes and seconds. Each degree is divided into 60 parts (minutes), and each minute is divided into 60 seconds. On the example of Moscow, the record looks like this: 55° 45′ 7″ N, 37° 36′ 56″ E or 55 degrees, 45 minutes, 7 seconds north latitude and 37 degrees, 36 minutes, 56 seconds south longitude.

The interval between the meridians is 15 degrees and about 111 km along the equator - this is the distance the Earth rotates in one hour. It takes 24 hours for a full turn, which is a day.

Use the globe

The model of the Earth is accurately reproduced on a globe with a realistic rendering of all continents, seas and oceans. As auxiliary lines, parallels and meridians are drawn on the map of the globe. Almost any globe has in its design a sickle-shaped meridian, which is installed on the base and serves as an auxiliary measure.

The meridian arc is equipped with a special degree scale, which determines the latitude. Longitude can be found using another scale - a hoop, horizontally installed at the level of the equator. Marking the desired place with your finger and rotating the globe around its axis to the auxiliary arc, we fix the latitude value (depending on the location of the object, it will turn out to be either north or south). Then we mark the data of the equator scale at the place of its intersection with the meridian arc and determine the longitude. To find out whether it is east or south longitude, you can only relative to the zero meridian.