Geographic longitude and latitude are used to accurately determine the physical location of any object on the globe. The easiest way to find geographic coordinates is to use a geographic map. This method requires some theoretical knowledge for its implementation. How to determine the longitude and latitude is described in the article.

Geographical coordinates

Coordinates in geography are a system in which each point on the surface of our planet is assigned a set of numbers and symbols that allows you to accurately determine the position of this point. Geographical coordinates are expressed in three numbers - this is latitude, longitude and height above sea level. The first two coordinates, that is, latitude and longitude, are most often used in various geographical tasks. The origin of the report in the geographic coordinate system is at the center of the Earth. Spherical coordinates are used to represent latitude and longitude, which are expressed in degrees.

Before considering the question of how to determine longitude and latitude by geography, you should understand these concepts in more detail.

The concept of latitude

The latitude of a particular point on the surface of the Earth is understood as the angle between the equatorial plane and the line connecting this point with the center of the Earth. Through all points on having the same latitude, you can draw a plane that will be parallel to the plane of the equator.

The plane of the equator is the zero parallel, that is, its latitude is 0 °, and it divides the entire globe into the southern and northern hemispheres. Accordingly, the north pole lies on parallel 90° north latitude and the south pole lies on parallel 90° south latitude. The distance that corresponds to 1° when moving along a particular parallel depends on which parallel it is. With increasing latitude when moving north or south, this distance decreases. Thus is 0°. Knowing that the circumference of the Earth at the latitude of the equator has a length of 40075.017 km, we obtain a length of 1 ° along this parallel equal to 111.319 km.

Latitude indicates how far north or south of the equator a given point lies on the Earth's surface.

The concept of longitude

The longitude of a particular point on the surface of the Earth is understood as the angle between the plane passing through this point and the axis of rotation of the Earth, and the plane of the prime meridian. According to the settlement agreement, the meridian is supposed to be zero, which passes through the Royal Observatory in Greenwich, located in the southeast in England. The Greenwich meridian divides the globe into east and

Thus, each line of longitude passes through the north and south poles. The lengths of all meridians are equal and amount to 40007.161 km. If we compare this figure with the length of the zero parallel, then we can say that the geometric shape of the planet Earth is a ball flattened from the poles.

Longitude shows how far west or east of the zero (Greenwich) meridian lies a specific point on Earth. If latitude has a maximum value of 90° (latitude of the poles), then the maximum value of longitude is 180° west or east of the prime meridian. The 180° meridian is known as the international date line.

One can ask an interesting question, the longitude of which points cannot be determined. Based on the definition of the meridian, we get that all 360 meridians pass through two points on the surface of our planet, these points are the south and north poles.

Geographic degree

From the above figures it can be seen that 1 ° on the Earth's surface corresponds to a distance of more than 100 km, both along the parallel and along the meridian. For more accurate coordinates of the object, the degree is divided into tenths and hundredths, for example, they talk about 35.79 north latitude. In this form, information is provided by satellite navigation systems such as GPS.

Ordinary geographical and topographic maps represent fractions of a degree in the form of minutes and seconds. So, each degree is divided into 60 minutes (denoted by 60"), and each minute is divided into 60 seconds (denoted by 60""). Here you can draw an analogy with the representation of the measurement of time.

Getting to know the map

To understand how to determine the geographical latitude and longitude on the map, you must first familiarize yourself with it. In particular, you need to figure out how the coordinates of longitude and latitude are represented on it. First, the top of the map shows the northern hemisphere, the bottom shows the southern. The numbers on the left and right of the edge of the map indicate latitude, and the numbers at the top and bottom of the map are longitude coordinates.

Before you determine the coordinates of latitude and longitude, you must remember that they are presented on the map in degrees, minutes and seconds. Do not confuse this system of units with decimal degrees. For example, 15" = 0.25°, 30" = 0.5°, 45"" = 0.75".

Using a geographic map to determine longitude and latitude

Let us explain in detail how to determine longitude and latitude by geography using a map. To do this, you first need to purchase a standard geographic map. This map can be a map of a small area, region, country, continent, or the whole world. To understand which card to deal with, you should read its name. At the bottom, under the name, the limits of latitudes and longitudes, which are presented on the map, can be given.

After that, you need to select some point on the map, some object that needs to be marked in some way, for example, with a pencil. How to determine the longitude of an object located at a selected point, and how to determine its latitude? The first step is to find the vertical and horizontal lines that lie closest to the selected point. These lines are the latitude and longitude, the numerical values ​​​​of which can be viewed at the edges of the map. Assume that the chosen point lies between 10° and 11° north latitude and 67° and 68° west longitude.

Thus, we know how to determine the geographic latitude and longitude of the object selected on the map with the accuracy that the map provides. In this case, the accuracy is 0.5°, both in latitude and longitude.

Determination of the exact value of geographical coordinates

How to determine the longitude and latitude of a point more precisely than 0.5 °? First you need to find out what scale the map with which you are working is. Usually, a scale bar is indicated in one of the corners of the map, showing the correspondence of distances on the map to distances in geographical coordinates and in kilometers on the ground.

After the scale bar is found, it is necessary to take a simple ruler with millimeter divisions and measure the distance on the scale bar. Let in this example, 50 mm corresponds to 1 ° latitude and 40 mm - 1 ° longitude.

Now we position the ruler so that it is parallel to the lines of longitude drawn on the map, and measure the distance from the point in question to one of the nearest parallels, for example, the distance to the 11 ° parallel is 35 mm. We make up a simple proportion and find that this distance corresponds to 0.3 ° from the 10 ° parallel. Thus, the latitude of the point under consideration is +10.3° (the plus sign means north latitude).

Similar actions should be done for longitude. To do this, place the ruler parallel to the lines of latitude and measure the distance to the nearest meridian from the selected point on the map, for example, this distance is 10 mm to the meridian of 67 ° west longitude. According to the rules of proportion, we obtain that the longitude of the object in question is -67.25 ° (the minus sign means longitude west).

Convert received degrees to minutes and seconds

As stated above, 1° = 60" = 3600"". Using this information and the rule of proportion, we find that 10.3° corresponds to 10°18"0"". For the longitude value, we get: 67.25 ° = 67 ° 15 "0"". In this case, the proportion was used once for the longitude and latitude for the conversion. However, in the general case, when fractional minutes are obtained after using the proportion once, it follows use the proportion a second time to get the value of incremental seconds. Note that the accuracy of determining the coordinates to 1 "corresponds to an accuracy on the surface of the globe equal to 30 meters.

Recording received coordinates

After the question of how to determine the longitude of an object and its latitude has been resolved, and the coordinates of the selected point have been determined, they should be written down correctly. The standard notation is to indicate the longitude after the latitude. Both values ​​must be specified with as many decimal places as possible, since the accuracy of the object location depends on this.

Certain coordinates can be represented in two different formats:

1. Using only the degree icon, e.g. +10.3°, -67.25°.
2. Using minutes and seconds, for example, 10°18"0"" North, 67°15"0"" West.

It should be noted that when representing geographic coordinates in degrees only, the words "North (South) latitude" and "East (West) longitude" are replaced by the appropriate plus or minus sign.

With such concepts as longitude and latitude, many of us met in childhood thanks to the adventure novels of Stevenson and Jules Verne. People have been studying these concepts since ancient times.


In an era when there were no perfect navigational instruments in the world, it was the geographical coordinates on the map that helped sailors determine their location in the sea and find their way to the desired land areas. Today, latitude and longitude are still used in many sciences and allow you to accurately determine the position of any point on the earth's surface.

What is latitude?

Latitude is used to set the location of an object relative to the poles. At the same distance from and passes the main imaginary line of the globe - the equator. It has zero latitude, and parallels stretch on both sides of it - similar imaginary lines that conditionally cross the planet at regular intervals. To the north of the equator are the northern latitudes, to the south, respectively, the southern ones.

The distance between the parallels is usually measured not in meters or kilometers, but in degrees, which allows you to more accurately determine the position of the object. There are 360 ​​degrees in total. Latitude is measured north of the equator, that is, points lying in the Northern Hemisphere have a positive latitude, and those located in the Southern Hemisphere have a negative one.

For example, the north pole lies at a latitude of +90°, the south pole at -90°. Additionally, each degree is divided into 60 minutes, and minutes into 60 seconds.

What is longitude?

To find out the location of an object, it is not enough to know this place on the globe relative to the south or north. In addition to latitude, longitude is used for a complete calculation, which sets the position of the point relative to east and west. If in the case of latitude the equator is taken as the basis, then longitude is calculated from the zero meridian (Greenwich), passing from the North to the South Pole through the London area of ​​Greenwich.

On the right and left sides of the Greenwich meridian, ordinary meridians are drawn parallel to it, which meet each other at the poles. East longitude is considered positive, and west longitude is negative.


Like latitude, longitude has 360 degrees divided into seconds and minutes. To the east of Greenwich is Eurasia, to the west - South and North America.

What are latitude and longitude for?

Imagine that you are sailing on a ship lost in the middle of the ocean, or moving through the endless desert, where there are no signs and indicators at all. How could you explain your location to rescuers? It is latitude and longitude that help to find a person or other object anywhere in the world, wherever he is.

Geographic coordinates are actively used on maps of search engines, in navigation, on ordinary maps. They are present in geodetic instruments, satellite positioning systems, GPS navigators and other tools needed to determine the location of a point.

How to set geographic coordinates on the map?

To calculate the coordinates of an object on the map, you must first determine in which of the hemispheres it is located. Next, you should find out between which parallels the desired point is located, and set the exact number of degrees - usually they are written on the sides of the geographical map. After that, you can proceed to the determination of longitude, first establishing in which of the hemispheres the object is located relative to Greenwich Mean Time.


Determination of degrees of longitude is carried out similarly to latitude. If you need to find out the location of a point in three-dimensional space, its height relative to sea level is additionally used.

Geographic coordinates and their definition on the map

Geographical coordinates- angular values ​​(latitude and longitude) that determine the position of objects on the earth's surface and on the map. They are divided into astronomical, obtained from astronomical observations, and geodetic, obtained from geodetic measurements on the earth's surface.

Astronomical coordinates determine the position of the points of the earth's surface on the surface of the geoid, where they are projected by plumb lines; geodetic coordinates determine the position of points on the surface of the earth's ellipsoid, where they are projected by normals to this surface.

The discrepancies between astronomical and geodetic coordinates are due to the deviation of the plumb line from the normal to the surface of the earth's ellipsoid. For most of the globe, they do not exceed 3-4 "" or in a linear measure 100 m. The maximum deviation of the sheer line reaches 40 "".

Used on topographic maps geodetic coordinates. In practice, when working with maps, they are usually called geographic.

The geographical coordinates of any point M are its latitude B and longitude L.

Point latitude- the angle formed by the plane of the equator and the normal to the surface of the earth's ellipsoid passing through the given point. Latitudes are counted along the arc of the meridian from the equator to the poles from 0 to 90o; in the northern hemisphere, latitudes are called northern (positive), in the southern - southern (negative).

point longitude- dihedral angle between the plane of the initial (Greenwich) meridian and the plane of the meridian of the given point. Longitude is counted along the arc of the equator or parallel in both directions from the prime meridian, from 0 to 180o. The longitude of points located to the east of Greenwich up to 180 o is called eastern (positive), to the west - western (negative).

Geographic (cartographic, degree) grid - an image on the map of lines of parallels and meridians; used to determine the geographical (geodesic) coordinates of points (objects) and target designation. On topographic maps, the lines of parallels and meridians are the inner frames of the sheets; their latitude and longitude are signed at the corners of each sheet.

The geographic grid is fully shown only on topographic maps at a scale of 1: 500,000 (parallels are drawn through 30 "and meridians through 20") and 1: 1,000,000 (parallels are drawn through 1o, and meridians through 40"). Inside each sheet maps on the lines of parallels and meridians are signed by their latitude and longitude, which allow you to determine geographical coordinates on a large gluing of maps.

On maps of scales 1: 25,000, 1: 50,000, 1: 100,000 and 1: 200,000, the sides of the frames are divided into segments equal in degrees to 1 ". 200,000) into parts of 10 "". In addition, inside each sheet of maps at scales of 1:50,000 and 1:100,000, the intersection of the middle parallels and the meridian is shown and is given from the digitization in degrees and minutes, and the outputs of minute divisions are given along the inner frame strokes 2-3 mm long, along which parallels and meridians can be drawn on a map glued from several sheets.

If the territory for which the map was created is located in the Western Hemisphere, then in the northwestern corner of the sheet frame, to the right of the meridian longitude signature, the inscription "West of Greenwich" is placed.

The determination of the geographical coordinates of a point on the map is carried out according to the parallels and meridians closest to it, the latitude and longitude of which are known. To do this, on maps of scales 1: 25,000 - 1: 200,000, you should first draw a parallel to the south of the point and west of the 0 meridian, connecting the corresponding strokes along the sides of the sheet frame with lines (Fig. 2). Then, segments are taken from the drawn lines to the determined point (Aa1, Aa2) Yu, applied to the degree scales on the sides of the frame and reports are produced. In the example in fig. 2 point A has coordinates B = 54o35"40"" north latitude, L= 37o41"30"" east longitude.

Drawing a point on the map by geographical coordinates. On the western and eastern sides of the frame of the map sheet, the readings corresponding to the latitude of the point are marked with dashes. The latitude reading starts from the digitization of the southern side of the frame and continues in minute and second intervals. Then a line is drawn through these lines - a parallel to the point.

In the same way, the meridian of the point passing through the point is built, only its longitude is counted along the southern and northern sides of the frame. The intersection of the parallel and the meridian will indicate the position of this point on the map.

On fig. Figure 2 gives an example of plotting point M on a map along the coordinates B = 54o38.4 "N, L = 37o34.4" E.

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Find the coordinates of a point on the map. Determine location

Sometimes you may need to accurately calculate the geographical coordinates of your location or some object, but you don’t have anything with you except a map. Learning how to determine latitude and longitude on a map is not difficult, you just need to get a clear understanding of what a coordinate system is and how to work with it.

The coordinate system is a kind of geographical "registration" that any point on the planet has. To determine the latitude and longitude of the desired object on the map, a grid of meridians and parallels applied over the canvas of any image of the area helps. Let's see how it can be used to find a geographic location.

What is a coordinate system

A system that reads the coordinates of any point, people came up with a long time ago. This system consists of parallels representing latitude and meridians representing longitude.

Since it was difficult to determine latitude and longitude by eye, a grid of longitudinal and transverse arcs, indicated by numbers, began to be applied over all types of geographical images.

What does latitude mean

The number responsible for the latitude of a place on the map indicates its distance relative to the equator - the farther the point is from it and closer to the pole, the more its digital value increases.

• On flat images, as well as on globes, spherical lines drawn horizontally and parallel to the equator - parallels - are responsible for latitude.
• At the equator, there is a zero parallel, towards the poles, the value in numbers increases.
• Parallel arcs are indicated in degrees, minutes, seconds, as angular measurements.
• From the equator towards the North Pole, the value will have positive values ​​​​from 0º to 90º, denoted by the symbols "N", that is, "Northern latitude".
• And from the equator towards the south - negative, from 0º to -90º, denoted by the symbols "south", that is, "southern latitude".
• The values ​​90º and -90º are at the peak of the poles.
• Latitudes close to the equator are called "low", and those close to the poles are called "high".

To determine the location relative to the equator of the required object, you just need to correlate its point with the nearest parallel, and then see what number is opposite it to the left and right behind the map field.

• If the point is located between the lines, you must first determine the nearest parallel.
• If it is north of the desired point, then the coordinate of the point will be smaller, so from the nearest horizontal arc, you need to subtract the difference in degrees to the object.
• If the nearest parallel is lower than the desired point, then the difference in degrees is added to its value, since the desired point will have a larger value.

Since it is sometimes difficult to determine the latitude and longitude on the map at a glance, they use a ruler with a pencil or a compass.

Remember! All points of the globe, and accordingly - on a map or globe, located along one parallel arc, will have the same value in degrees.

What does longitude mean

Meridians are responsible for longitude - vertical spherical arcs converging at the poles to one point, dividing the globe into 2 hemispheres - western or eastern, which we are used to seeing on the map in the form of two circles.

• Meridians similarly make it easier to determine the exact latitude and longitude of any point on earth, since the place where they intersect with each of the parallels is easily indicated by a digital mark.
• The value of vertical arcs is also measured in angular degrees, minutes, seconds, ranging from 0º to 180º.
• Starting from 1884, it was decided to take the Greenwich meridian as a zero mark.
• All values ​​of coordinates in the direction of the west from Greenwich are denoted by the symbol "west longitude", that is, "west longitude".
• All values ​​in the direction east of Greenwich are indicated by the symbol "E", that is, "East longitude".
• All points located along the same arc of the meridian will have the same designation in degrees.

Remember! To calculate the value of longitude, you need to correlate the location of the desired object with the digital designation of the nearest meridian, which is placed outside the image fields above and below.

How to find the coordinates of the desired point

Often the question arises of how to determine the latitude and longitude on the map, if the desired point, remote from the coordinate grid, is inside the square.

The calculation of coordinates is also difficult when the image of the area has a huge scale, but there is no more detailed one with you.

• Here you can’t do without special calculations - you need a ruler with a pencil or a compass.
• First, the nearest parallel and meridian are determined.
• Their digital designation is fixed, then the step.
• Further, from each of the arcs, the distance is measured in millimeters, then converted to kilometers using a scale.
• All this corresponds to the step of the parallels, as well as the step of the meridians plotted on a certain scale.
• There are images with different steps - 15º, 10º, and there are less than 4º, it directly depends on the scale.
• Having learned the distance between the nearest arcs, also the value in degrees, you need to calculate the difference by how many degrees the given point deviates from the coordinate grid.
• Parallel - if the object is in the northern hemisphere, then we add the difference obtained to the smaller number, subtract from the larger one, for the southern one this rule works similarly, only we carry out calculations, as with positive numbers, but the final figure will be negative.
• Meridian - the position of a given point in the eastern or western hemisphere does not affect the calculations, we add our calculations to the smaller value of the parallel, subtract from the larger one.

It is also easy to calculate the geographic location with a compass - to get the value of the parallel, you need to put its ends on the point of the desired object and the nearest horizontal arc, and then transfer the spreader of the compass to the scale of the existing map. And to find out the value of the meridian, repeat all this with the nearest vertical arc.