Today, there is not a single site left on Earth that a person would not have studied or at least not visited! The more information appeared about the surface of the planet, the more urgent the question arose of determining the location of an 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
Mankind did not immediately come to such a simple method 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 create a modern map with a convenient degree grid.
- One of the "ancestors" natural sciences considered - Aristotle, who first proved that our planet has a spherical shape.
- The ancient travelers of the Earth were very observant, and they noticed that in the sky (by the stars), the direction C (north) - South (south) is 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 a lot of small and big discoveries that influenced the formation of geodesy. He was the first to use skafis (ancient sundial) to calculate the height of the sun over the territory of different cities and noticed a significant difference in their measurements, which depended on the time of day and season. Eratosthenes revealed the connection between such sciences as geodesy and astronomy, thereby making it possible to carry out many studies and measurements of terrestrial territories using celestial bodies.
Graticule
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 built in such a way that different squares are considered on separate pages, which makes it possible 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 cards have mandatory elements that make up the graticule. It is used to determine the coordinates.
Elements of the graticule
- The poles - North (above) and South (below) are the points where the meridians converge. They are the exit points of the virtual line, which is called the axis.
- polar circles. The boundaries of the polar regions begin with them. The polar circles (South and North) are located further than 23 parallels towards the poles.
- It divides the surface of the Earth into East and has two more names: Greenwich and Initial. 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?
Every 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 one and the same action, since it is the degree of the main lines that determines the geographical address of the desired territory. Below is a plan of action that can be used when calculating coordinates.
Algorithm of the address of the object on the map
- Check correctness geographical name object. Annoying errors happen due to banal inattention, for example: the 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 object you are looking for.
- Select the largest map from the atlas that contains the desired geographic point. The smaller the scale of the map, the more errors occur in the calculations.
- Determine the relationship of the object to the main elements of the grid. The algorithm of this procedure is presented after the paragraph: "Calculation of the size of the territory."
- If the desired point is not located directly on the line indicated on the map, then find the nearest ones that 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 the coordinates, it is important to find out how many degrees the parallels and meridians are located on the map and correctly calculate the desired 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.
Calculation of 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 equal to - 111 km.
- To determine the length of an object from W to E (if it is completely located in one of the hemispheres: Eastern or Western), it is enough from the larger value of the latitude of one of the extreme points, subtract the smaller one and multiply the resulting number by 111 km.
- If you need to calculate the length of the 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 greater 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 the object, then to calculate its length from W to E, the degrees of latitude of the extreme points of this direction are added, then their sum is multiplied by 111 km.
- If the equator is located on the territory of the object being determined, then to determine its length from N to S, it is necessary to add the degrees of longitude of the extreme points of this direction, and multiply the resulting amount by 111 km.
How to determine the relation of an object to the main elements of the graticule?
- If the object is below the equator, then its latitude will be only south, if it is above - north.
- If the desired point is located to the right of the initial meridian, then its longitude will be east, if to the left - west.
- If the object is located above the 66th degree of the 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, then the process of determining their geographical address is accompanied by many questions. Below are options for calculating coordinates high territories 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 decisive for the address of this system? AT this case focus on the most highest point. That is, the coordinates mountain system The Caucasus is the geographic address of the Elbrus peak, which is equal to - 42 degrees 30 minutes north latitude and 45 degrees east longitude.
Himalayas
The highest system of mountains on our mainland is the Himalayas. Meridians and parallels, having different degrees, cross this object as often as the above one. How to correctly determine the coordinates of this system? We act in the same way 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 Chomolungma peak, and this is 29 degrees 49 minutes north latitude and 83 degrees 23 minutes and 31 seconds east longitude.
Ural mountains
The longest on our mainland are the Ural Mountains. Meridians and parallels having different degree values intersect this object in various 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 east longitude. A similar way of determining the coordinates of mountains is acceptable for systems that have a large extent in one of the directions or in both.
If our planet is “cut” through the axis of rotation and perpendicular to it by many planes, then vertical and horizontal circles will appear on the surface - meridians and parallels.
The meridians will converge at their ends at two points - at the North and South Poles. Parallels, as the name implies, are parallel to each other. Meridians are used to measure longitude, parallels - latitude.
Such a simple action at a superficial glance - the "line" of the Earth - was the greatest discovery in the study of the planet. It made it possible to use coordinates and accurately describe the location of any object. Without parallels and meridians, it is impossible to imagine any map, not a single globe. And they came up with ... in the III century BC, the Alexandrian scientist Eratosthenes.
Reference. Eratosthenes possessed encyclopedic knowledge for those times in all areas. He was in charge of the legendary Library of Alexandria, wrote the work "Geography" and became the founder of geography as a science, compiled the first map of the world and covered it with a degree grid of verticals and horizontals - he invented a coordinate system. He also introduced the names for the lines - parallel and meridian.
Meridian
Meridian in geography is called half of the line of section earth's surface drawn through and any point on the surface. All imaginary meridians, of which there can be an infinite number, are connected at the poles - North and South. The length of each of them is 20,004,276 meters.
Although you can mentally draw as many meridians as you like, for the convenience of movement, mapping their number, their location was streamlined by international treaties. In 1884, at the International Meridian Conference in Washington, it was decided that the initial meridian (zero) would be the one that passes through Greenwich, a district in southeast London.
However, not everyone immediately agreed with this decision. For example, in Russia, even after 1884 until the beginning of the 20th century, the zero meridian was considered to be its own - Pulkovo: it "passes" through the Round Hall of the Pulkovo Observatory.
Prime Meridian
The zero meridian is the reference point of geographic longitude. He, respectively, has a zero longitude. This was before the creation of the world's first satellite navigation system Transit. 
With her appearance Prime Meridian I had to move a little - 5.3 "relative to Greenwich. This is how the International Reference Meridian appeared, which is used as a longitude reference point by the International Earth Rotation Service.
Parallel
Parallels in geography are called lines of an imaginary section of the surface of the planet by planes that are parallel to the equatorial plane. The parallels depicted on the globe are circles parallel to the equator. They are used to measure latitude.
By analogy with the Greenwich zero meridian, there is also a zero parallel - this is the equator, one of the 5 main parallels that divides the Earth into hemispheres - southern and northern. Other main parallels are the tropics North and South, the polar circles - North and South.
Equator
The longest parallel is the equator - 40,075,696 m. The rotation speed of our planet at the equator is 465 m / s - this is much more than the speed of sound in the air - 331 m / s.
Southern and Northern tropics
The Tropic of South, also called the Tropic of Capricorn, lies south of the equator and represents the latitude over which the midday sun is at its zenith on the winter solstice.
The northern tropic, also known as the tropic of Cancer, is located north of the equator and, like the southern tropic, represents the latitude over which the midday sun is at its zenith on the summer solstice.
Arctic Circle and Antarctic Circle
The Arctic Circle is the boundary of the polar day region. To the north of it, in any place at least once a year, the sun is visible above the horizon 24 hours a day, or the same amount is not visible.
The southern polar circle is similar in everything to the northern one, only it is located in the southern hemisphere.
Graticule
The intersections of meridians and parallels form a degree grid. Meridians and parallels are spaced at intervals of 10° - 20°, smaller divisions, as in the corners, are called minutes and seconds. 
With the help of a degree grid, we determine the exact location of geographical objects - their geographical coordinates, calculating longitude by meridians, and latitude by parallels.
Points of intersection of the earth's axis with the surface the globe are called poles (North and South). The Earth rotates once around this axis in 24 hours.
A circle is drawn at the same distance from the poles, which is called the equator.
Parallel - lines conventionally drawn on the surface of the Earth parallel to the equator. The parallels on the map and the globe are directed to the west and east. They are not equal in length. The longest parallel is the equator. The equator is an imaginary line on the earth's surface, obtained by mentally dissecting an ellipsoid into two equal parts (Northern and Southern hemispheres). With such a dissection, all points of the equator are equidistant from the poles. The plane of the equator is perpendicular to the Earth's axis of rotation and passes through its center. In total, there are 180 meridians on Earth, 90 of them are north of the equator, 90 are south.
The parallels of 23.5° north and south are called tropical circles or simply tropics. On each of them, once a year, the midday Sun is at its zenith, i.e. Sun rays fall steeply.
The parallels of 66.5° northern and southern latitudes are called polar circles.
Circles are drawn through the North and South Poles, meridians are the shortest lines conventionally drawn on the surface of the Earth from one pole to another.
The prime or prime meridian was drawn from the Greenwich Observatory (London, UK). All meridians have the same length and the shape of semicircles. In total, there are 360 meridians on Earth, 180 to the west of zero, 180 to the east. Meridians on the map and globe are directed from north to south.
For exact definition the location of any object on the surface of the earth, one line of the equator is not enough. Therefore, the hemispheres are mentally separated by many more planes, parallel to the plane The equator is a parallel. All of them, like the plane of the equator, are perpendicular to the axis of rotation of the planet. You can draw as many parallels as you like, but they are usually drawn at intervals of 10-20 °. Parallels are always oriented from west to east. The circumference of the parallels decreases from the equator to the poles. At the equator, it is the largest, and at the poles it is zero:
Length of arcs of parallels
|
Parallels |
Length 1° in km |
When the globe is crossed by imaginary planes passing through the axis of the Earth perpendicular to the plane of the equator, large circles are formed - meridians. Translated into Russian, the word "meridian" means "midday line". Indeed, their direction coincides with the direction of the shadow from objects at noon. If you go all the time in the direction of this shadow, you will definitely come to the North Pole. Meridians are the shortest line conventionally drawn from one pole to another. All meridians are semicircles. They can be drawn through any point on the surface of the Earth. They all intersect at the poles. The meridians are oriented from north to south. The average arc length of 1° meridian is calculated as follows:
40,008.5 km: 360° = 111 km
All meridians are the same length. 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 shows the direction to the north, in the Southern - to the south.
Image of lines of meridians and parallels on the globe and geographical maps ah is called a graticule.
Geographic latitude is the distance of any point on the earth's surface north or south of the equator, expressed in degrees. Latitude is north (if the point is located north of the equator) and south (if south of it).
Geographic longitude is the distance of any point on the earth's surface from the prime meridian, expressed in degrees. To the east of the zero meridian will be eastern longitude (abbreviated: east longitude), to the west - western (west longitude).
Geographical coordinates - geographical latitude and geographic longitude of the given object.
1 slide
Degree network on the globe and geographical map The presentation was prepared by Nekhayeva E.A.
2 slide
Review What is a geographic map? How is a map different from a map? Why is it impossible to accurately judge the size and shape of objects on a map? Select the scale of geographical maps: A) 1: 500 B) 1: 500,000 C) 1: 1,000 D) 1:2,500,000 E) 1:25,000,000
3 slide
The degree network is formed by meridians and parallels drawn through a certain number of degrees. Meridians and parallels are imaginary lines that help distinguish between north and south, west and east, they can be used to measure distances, find objects on a globe and a map.
4 slide
Parallels Decreasing to the north and south, They managed to keep the shape of the circle. They are all parallel to each other, That's why they are called parallels. The biggest one is called the equator, the smallest one is the pole point. Everything from the east stretches to the west, And they search for latitudes along them. Points of the Earth through which the imaginary earth's axis passes A line drawn at the same distance from the poles. What continents does the equator cross? What hemispheres does the equator divide the globe into? Northern Hemisphere Southern Hemisphere Which continents are located in both the northern and southern hemispheres?
5 slide
6 slide
Parallel - a line conventionally drawn on the surface of the Earth parallel to the equator Determine the longest parallel. Find the shortest parallel. What direction do the parallels show? west east What is the length of the parallels in kilometers? What is the length of the parallels in degrees? What shape do parallels have on a globe What shape do parallels have on a map of the hemispheres Workbook p. 21, task 4 The length of the equator is 40,000 km, in degrees - 360˚. Determine how many kilometers are in one degree of the meridian at the equator? 40,000: 360 = 111 km physical map hemispheres determine how many kilometers in 1 degree of the meridian on the parallel 10 ˚, 20 ˚, 80 ˚ in the northern hemisphere?
7 slide
Features Meridians Parallels Direction to the sides of the horizon West-East Start of report Equator End of reference North and South Pole Length in degrees 90 0+90 0 Length in km From 40,000 to 0 Length 1 0 in km Different from 111 to 0 Shape on a circle globe Shape on the map of the hemispheres Arcs of different sizes, the equator is a straight line
8 slide
Meridians Translated into Russian, the word "meridian" means "midday line". How can such a name be explained (Fig. 17 p. 28). What meridians are the beginning and end of the countdown? What hemispheres divide the globe 0 Greenwich and 180 meridian? What continents are located in both the western and eastern hemispheres? Eastern Hemisphere Western Hemisphere
9 slide
10 slide
A meridian is the shortest line conventionally drawn on the surface of the Earth from one pole to another. Workbook p. 21, task 4 What direction do the meridians show? north south What is the length of the meridian in kilometers? What is the length of the meridian in degrees? What shape are the meridians on the globe? What shape are the meridians on the map? The length of each meridian is 20,000 km, in degrees 180˚. Determine how many kilometers are in 1 ˚ meridian? 20,000: 180˚ = 111 km
11 slide
Features Meridians Parallels Direction to the sides of the horizon North - south West - east Beginning of the report Zero or Greenwich Equator End of reference 180 meridian North and South Pole Length in degrees 180 +180 90 0+90 0 Length in km 20 000 From 40 000 to 0 Length 1 0 in km 111 Different from 111 to 0 Shape on a globe of a semicircle of a circle Shape on a map of the hemispheres Arcs of equal size, straight line in the center Arcs of different sizes, equator-straight line
Parallels, meridians and the degree network they form allow you to accurately indicate any places on the surface of the Earth.
Parallels are circles parallel to the equator. The equator is taken as 0°. Those circles that are in the northern hemisphere are designated as follows: 10 ° N. latitude, 35° N sh. etc. The parallels of the southern hemisphere are signed with the abbreviation y. sh.
It is clear that parallels can be drawn as many as you like. It can be carried out through one degree, it is possible through ten, and it is possible through a fraction of one degree. It all depends on the accuracy of the measurement.
meridians are lines drawn from North Pole to the South. They are semicircles. They can also be carried out as many as you like, depending on the accuracy of the measurement. The origin of the meridians was chosen arbitrarily (that is, there was no reason for this related to the features of the Earth), and it is located in Greenwich (it is a suburb of London). Meridians are also measured in degrees with a signature c. d. (east longitude) or s. D. (West longitude).
Intersecting parallels and meridians form degree network . Any point from the intersection can be uniquely determined. For example, 23° N. latitude, 55° east e. It is this method that is used to determine any object, terrain on the surface of the Earth.
Parallels and meridians can also be measured in kilometers.