As a child, I could not understand why strange lines were drawn on the globe. With complete confidence that I was right, I proved to my classmates that they were real. One day we even planned for everyone in first and second grade to go in search of them, but, thank God, our teacher explained to us what was what. Why do we need non-existent stripes??
Let's figure it out.
Parallel - what is it?
Strange stripes on the map indicate nothing more than latitude and longitude. For example, let's imagine ourselves standing next to a huge school globe. Personally, in our class he had not only the designations of parallels and meridians, but also the signatures of all the school bullies and the prints of children's hands. In general, that's not the point. The rod in the school globe is an imaginary axis of the planet, which connects opposite poles. Also between them is equator. On the globe it is often indicated as the horizontal connection of our makeshift planet. Equatorial latitude is indicated by zero, and above and below there are lines with an increasing index. All parallels reflect their quantitative sign and measured in degrees relative to the equator.
Meridians - designation of planetary longitude
And yet, breadth alone will not be enough for us. To find out the location of an object we need to know the position of a point relative to other cardinal directions. The meridian, designated zero, passes through the observatory at Greenwich and divides the Earth into two hemispheres - western and eastern. All longitudes also have their own digital designation and are calculated in degrees relative to the Greenwich meridian. We have seen more than once on maps that they do not intersect and are united only at the pole.
Let's summarize the information:
- strange stripes on the map indicate longitude or latitude;
- equator - latitude designated by zero, divides the planet into North and South;
- the meridian, designated zero, passes through Greenwich and divides the Earth from West to East;
- axis - connects opposite poles.
Why are these strange stripes needed?
It's simple - for orientation within the world. Any point on the planet is simply an intersection of parallels and meridians, and thanks to this coordinate system, we have made our life much easier. For example, the work of pilots would be very complicated without the existence of parallels and meridians.
Today there is not a single area left on Earth that has not been studied by man or at least visited! The more information appeared about the surface of the planet, the more pressing the question arose of determining the location of this or that object. Meridians and parallels, which are elements of the degree grid, help to find the geographic address of the desired point and facilitate the process of orienting on the map.
History of cartography
Humanity did not immediately come to such a simple way of determining the coordinates of an object as calculating its longitude and latitude. Familiar to all of us from school, the main lines gradually appeared in the sources of cartographic knowledge. Below is information about several key stages in the history of the formation of such sciences as geography and astronomy, which led civilization to the creation of a modern map with a convenient degree grid.
- One of the “founders” of natural sciences is Aristotle, who was the first to prove that our planet has a spherical shape.
- The ancient travelers of the Earth were very observant, and they noticed that in the sky (according to the stars), the direction N (north) - S (south) can be easily traced. This line became the first “meridian”, an analogue of which today can be found on the simplest map.
- Eratosthenes, who is better known as the “father of the science of geography,” made many small and large discoveries that influenced the development of geodesy. He was the first to use a skafis (ancient sundial) to calculate the height of the sun over the territory of different cities and noticed a significant difference in his measurements, which depended on the time of day and season. Eratosthenes identified the connection between sciences such as geodesy and astronomy, thereby making it possible to carry out many studies and measurements of terrestrial territories using celestial bodies.
Degree grid
Numerous meridians and parallels, intersecting on a map or globe, are connected into a geographical grid consisting of “squares”. Each of its cells is limited by lines that have their own degree. Thus, using this grid you can quickly find the desired object. The structure of many atlases is designed in such a way that different squares are considered on separate pages, which allows you to systematically study any territory. With the development of geographical knowledge, the globe also improved. Meridians and parallels are available on the very first models, which, although they did not contain all the reliable information about the objects of the Earth, already gave an idea of the approximate location of the desired points. Modern maps have mandatory elements that make up the degree grid. Using it, coordinates are determined.
Elements of the degree grid
- The North (above) and South (below) poles are the points at which the meridians converge. They are the exit points of a virtual line called an axis.
- Polar circles. The boundaries of the polar regions begin with them. The Arctic Circles (Southern and Northern) are located beyond the 23rd parallel towards the poles.
- It divides the surface of the Earth into Eastern and and has two more names: Greenwich and Primary. All meridians have the same length and connect the poles on the surface of a globe or map.
- Equator. It is oriented from W (west) to E (east), which divides the planet into the Southern and Northern hemispheres. All other lines parallel to the equator have different sizes - their length decreases towards the poles.
- Tropics. There are also two of them - Capricorn (South) and Cancer are located on the 66th parallel south and north of the equator.
How to determine the meridians and parallels of the desired point?
Any object on our planet has its own latitude and longitude! Even if it is very, very small or, conversely, quite large! Determining the meridians and parallels of an object and finding the coordinates of a point is the same action, since it is the degree of the main lines that determines the geographic address of the desired territory. Below is a plan of action that can be used when calculating coordinates.
Algorithm for the address of an object on the map
- Check the correct geographical name of the object. Annoying mistakes happen due to simple inattention, for example: a student made a mistake in the name of the desired point and determined the wrong coordinates.
- Prepare an atlas, a sharp pencil or pointer and a magnifying glass. These tools will help you more accurately determine the address of the desired object.
- Select the largest scale map from the atlas that shows the desired geographic point. The smaller the map scale, the more errors appear in the calculations.
- Determine the relationship of the object to the main mesh elements. The algorithm for this procedure is presented after the point: “Calculating the size of the territory.”
- If the desired point is not located directly on the line marked on the map, then find the nearest ones, which have a digital designation. The degree of lines is usually indicated along the perimeter of the map, less often - on the equator line.
- When determining coordinates, it is important to find out how many degrees the parallels and meridians are located on the map and correctly calculate the required ones. It must be remembered that the elements of the degree grid, except for the main lines, can be drawn through any point on the Earth's surface.
Calculating the size of the territory
- If you need to calculate the size of an object in kilometers, then you need to remember that the length of one degree of grid lines is 111 km.
- To determine the extent of an object from W to E (if it is completely located in one of the hemispheres: Eastern or Western), it is enough to subtract the smaller value from the larger value of the latitude of one of the extreme points and multiply the resulting number by 111 km.
- If you need to calculate the length of a territory from N to S (only if it is all located in one of the hemispheres: Southern or Northern), then you need to subtract the smaller one from the larger degree of longitude of one of the extreme points, then multiply the resulting amount by 111 km .
- If the Greenwich meridian passes through the territory of an object, then to calculate its length from W to E, the degrees of latitude of the extreme points of a given direction are added, then their sum is multiplied by 111 km.
- If the equator is located on the territory of the designated object, then to determine its extent from N to S it is necessary to add the degrees of longitude of the extreme points of this direction, and multiply the resulting sum by 111 km.
How to determine the relationship of an object to the main elements of the degree grid?
- If an object is located below the equator, then its latitude will be only southern, if above - northern.
- If the desired point is located to the right of the prime meridian, then its longitude will be eastern, if to the left - western.
- If an object is located above the 66th degree north or south parallel, then it enters the corresponding polar region.
Determining the coordinates of mountains
Since many mountain systems have a large extent in different directions, and the meridians and parallels crossing such objects have different degrees, the process of determining their geographical address is accompanied by many questions. Below are options for calculating the coordinates of the high territories of Eurasia.
Caucasus
The most picturesque mountains are located between two water areas of the mainland: from the Black Sea to the Caspian Sea. Meridians and parallels have different degrees, so which ones should be considered determining for the address of a given system? In this case, we focus on the highest point. That is, the coordinates of the Caucasus mountain system are the geographical address of Elbrus peak, which is equal to 42 degrees 30 minutes north latitude and 45 degrees east longitude.
Himalayas
The highest mountain system on our continent is the Himalayas. Meridians and parallels, having different degrees, intersect this object as often as the above-mentioned one. How to correctly determine the coordinates of this system? We do the same as in the case of the Ural Mountains, we focus on the highest point of the system. Thus, the coordinates of the Himalayas coincide with the address of the Qomolungma peak, and it is 29 degrees 49 minutes north latitude and 83 degrees 23 minutes and 31 seconds east longitude.
Ural Mountains
The longest on our continent are the Ural Mountains. Meridians and parallels, having different degrees, intersect a given object in different directions. To determine the coordinates of the Ural Mountains, you need to find their center on the map. This point will be the geographic address of this object - 60 degrees north latitude and the same eastern longitude. This method of determining the coordinates of mountains is acceptable for systems that have a large extent in one of the directions or in both.
“And cities and countries, parallels, meridians flash by,” is sung in a song called “Globe.” But if the cities and countries indicated on the globe exist in reality, then parallels and meridians are imaginary objects, marked on the globe or map solely for ease of reading and orientation.
The best assistant in orientation is a coordinate system, which must have a reference point. For the Earth (however, the same principle can be applied to any other planet or its satellite - there would be a reason for it) such an imaginary “zero point” was determined with the help of poles - points through which its axis of rotation passes. The North Pole is a rather mathematical object, it is located in the Arctic Ocean, but the South Pole is a very real point on land, on a continent called Antarctica, you can get there, you can take pictures there - if you are not afraid of freezing, of course...
So, at an equal distance from these same poles, in the middle between them, there is an imaginary “belt” of the Earth, dividing the planet in half, into the Northern and Southern Hemispheres. Most continents are in one of them, and only Africa is in both. So, the equator is the “reference point”, which is considered zero latitude. Imaginary lines drawn on a map and globe parallel to the equator are called parallels.
Latitude is measured in degrees, 1 degree is approximately 111 km. It is calculated from the equator (the farther from it, the larger the number: equator - 0 degrees, poles - 90 degrees). North of the equator is the degree of northern latitude, and to the south is the degree of east longitude. There is another way of notation: south of the equator, latitude is written with a minus sign (this can be understood: those who created the science of geography lived in the Northern Hemisphere, and their shirt, as you know, is closer to the body).
All this, of course, is wonderful, but...
Let us recall J. Verne’s novel “The Children of Captain Grant.” The heroes who went to help Captain Grant and his companions who survived the shipwreck knew that their location was thirty-seven degrees eleven minutes south latitude. To find them, the heroes had to travel around the world along this parallel.
To avoid such difficulties, there is a second coordinate - longitude, and on the map it is indicated by meridians - lines connecting the poles.
If we wanted to choose a parallel for the longest trip around the world, it would undoubtedly be the equator. But choosing a meridian for such a matter will not work - they are approximately the same, so choosing a reference point among them is not so easy, so for a long time there was discrepancy in this regard: in France the Paris meridian was taken as the reference point, in Russia - passing through Pulkovo Observatory, etc. Finally, in 1884, at the International Conference in Washington, a single reference point was adopted - the meridian passing through the axis of the passage instrument of the observatory in Greenwich, an administrative district of London on the right bank of the Thames. It is from the Greenwich meridian that the western and eastern longitudes are calculated (the heroes of the mentioned novel were unlucky: the longitude in the note was washed away by water).
The number of kilometers in one degree of longitude is more difficult to name than in relation to latitude: it is not the same at different latitudes - at the equator it is also 11 km, and the closer to the poles - the less).
Questions before a paragraph
1. What lines does the degree network of the globe consist of?
From meridians and parallels.
2. What shape and what directions do the parallels and meridians on the globe have?
All the earth's meridians pass through the North and South geographic poles. On the globe, the meridian lines are semicircles of equal length. Parallels are drawn perpendicular to the meridians - circles, all points of which are equidistant from the geographic pole. The lengths of the parallels decrease with distance from the equator to the poles.
3. Through which two points on the surface of the Earth do all meridians pass?
All meridians on the surface of the earth pass through the points of the north and south poles.
Questions and tasks
1. In which hemispheres is Russia located?
Russia is located entirely in the Northern Hemisphere, most of Russia's territory is located in the Eastern Hemisphere, but the eastern part of the Chukotka Autonomous Okrug is located in the Western Hemisphere.
2. Using a globe, determine the geographic coordinates of the highest peak in the world - Mount Everest (Chomolungma).
Everest is considered the highest (largest) peak in the whole world, the mountain is located on the territory of China and Nepal, its geographical data is 27° 59' 16" (27° 59' 27) northern latitude, 86° 55' 31" (86° 55' 51 ) east longitude. The height of this relief is 8848.43 meters (above the sea). It has a cold climate, strong winds of 200 km per hour and low temperatures of -60 °C.
3. Which parallel, a multiple of 10, crosses three continents: Africa, Eurasia and South America?
The tenth parallel of northern latitude runs across the African continent through eleven countries - Guinea, Ivory Coast, Ghana, Togo, Benin, Nigeria, Cameroon, Chad, Sudan, Ethiopia and Somalia.
Eurasia touches the tenth parallel with three countries: India, Thailand, and Vietnam.
The territories of Colombia and Venezuela meet this parallel in South America.
4. What meridians, multiples of 10, cross two continents: North and South America?
These two continents are crossed by the 60th, 70th and 80th meridians of western longitude.
The 60th meridian passes through countries such as Canada, Venezuela, Guyana, Brazil, Bolivia, Paraguay and Argentina.
Longitude 70 runs through North America through Canada and the USA and then through South America through Venezuela, Colombia, Brazil, Peru, Chile and Argentina.
80 meridians - through four countries - Canada, USA, Ecuador and Peru.
5. From what point on the Earth’s surface can you start moving only in a southerly direction?
The North Pole is located at the highest point of the earth's axis, where all meridians converge and the parallels narrow until there is no radius at all. There is no rotation that defines the western and eastern sides of the horizon. There is also no northern direction, because there is nowhere to go further. The only road left is to the south, no matter which direction the traveler goes when he climbs to the very top of the planet.
6. How do you indicate the geographic latitude of points? At how many degrees are the parallels drawn?
The geographic latitude of a point on the Earth's surface is the value of the meridian segment between a given point and the equator, expressed in degrees. Geographic latitudes are measured from the equator; all points lying on the equator have the same geographic latitude - 0 degrees. w. All points lying in the Northern Hemisphere have a northern latitude (N) from 0 to 90 degrees, and points lying in the Southern Hemisphere have a southern latitude (S) from 0 to 90 degrees. Typically, parallels are drawn on the globe in multiples of 10, 15 or 20 degrees.
7. How do you indicate the geographic longitude of points? How many degrees are the meridians separated from?
The longitude of geographic points is indicated on the map using meridian lines, or simply meridians. All points located east of the Greenwich (prime) meridian have an east longitude (E) from 0 to 180 degrees, and points located west of Greenwich have a west longitude (W) from 0 to 180 degrees. Typically, on a globe, meridians, like parallels, are drawn at 10, 15 or 20 degrees.
>> Degree network, its elements. Geographical coordinates
§ 3. Degree network, its elements. Geographical coordinates
You can navigate using a map and find the exact location of geographic objects on the Earth’s surface. degree network, or a system of lines of parallels and meridians.
Parallels(from the Greek parallelos - letters, walking next to) - these are lines conventionally drawn on the surface of the Earth parallel to the equator. Parallels on the map and globe You can carry out as many as you like, but usually on training maps they are carried out at intervals of 10-20°. The parallels are always oriented from west to east. The circumference of the parallels decreases from the equator to the poles.
Equator(from Latin aequator - equalizer) - an imaginary line on the earth's surface, obtained by mentally dissecting the globe with a plane passing through the center of the Earth perpendicular to its axis of rotation. All points on the equator are equidistant from the poles. The equator divides the globe into two hemispheres - Northern and Southern.
Meridian(from Latin meridians - midday) - the shortest line conventionally drawn on the surface of the Earth from one pole to the other.
table 2
Comparative characteristics of meridians and parallels
Geographic poles(from Latin polus - axis) - mathematically calculated points of intersection of the imaginary axis of rotation of the Earth with the earth's surface. Meridians can be drawn through any points on the earth's surface, and they will all pass through both poles of the earth. The meridians are oriented from north to south, and all have the same length (from pole to pole) - about 20,000 km. Average length of 1° meridian: 20004 km: 180° = 111 km. The direction of the local meridian at any point can be determined at noon by the shadow of any object. In the Northern Hemisphere, the end of the shadow always points north, in the Southern Hemisphere - south.
degree, or cartographic, network serves to determine geographic coordinates points of the earth's surface - longitudes and latitudes - or mapping objects according to their coordinates. All points of a given meridian have the same longitude, and all points of the parallel have the same latitude.
Geographic latitude is the magnitude of the meridian arc in degrees from the equator to a given point. Thus, St. Petersburg is located in the Northern Hemisphere, at 60° north latitude (abbreviated as N), the Suez Canal is at 30° north latitude. To determine the geographic latitude of any point on a globe or map is to determine on which parallel it is located. South of the equator, any point will have a southern latitude (abbreviated as S).
Geographic longitude is the magnitude of the parallel arc in degrees from the prime meridian to a given point. The prime, or prime, meridian is chosen arbitrarily and passes through the Greenwich Observatory, located near London. To the east of this meridian, eastern longitude (E) is determined, to the west - western longitude (W) (Fig. 10).
The latitude and longitude of any point on Earth constitute its graphic coordinates. Thus, the geographic coordinates of Moscow are 56° N. and 38° east. d.
Maksakovsky V.P., Petrova N.N., Physical and economic geography of the world. - M.: Iris-press, 2010. - 368 pp.: ill.
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