What directions are determined by parallels. Degree grid: parallels, equator, meridians, prime meridian

Today our associations associated with travel have changed a lot. "Unlucky Notes", "Heads and Tails" against the background of the cheapness of All Inclusive in comparison with the soviet did their job. Does anyone now remember about "parallels, meridians"? Well, at least a song, huh?

Okay, let's recall. Only cities and countries will not flicker - surprisingly, but the parallels with the meridians and next to us are :)

Haven't you guessed what we're talking about yet? ;)
Then let's start from afar.
As a child, I had a globe on my desk. How to read Jules Verne without a globe ?!
And now the hand does not rise to buy this invention - it is a luxury item. And, as it were, irrelevant in the age of Google Maps and Yandex Sputnik.

But I'm not talking about the globe. The journey in search of Captain Grant made the imaginary lines on the globe real, almost tangible. A person's addiction to imaginary lines is understandable, because they symbolize the elusive mystery of Being. Yet again pirate maps, treasures and adventures. All thirty-three pleasures. The silhouette of the steering wheel or the ringing of the ship's bell alone triggers the imagination and makes our hearts beat! This is not a booking with a choice between BB, HB and AI.

But the Caribbean is too far away, the pirates are too long ago, and all this, combined together by the film business, turns into fantasy, killing the very real romance of distant wanderings. And if you ask what parallel Cheboksary is on, some will be surprised: "But what, do we have parallels too?"
And when they find out that the 56th parallel runs a little to the south, they will say in disappointment: "Ah, well, I thought so, where can we ...".

Well, here it is, the 56th parallel, here, look. It is 56 ° north latitude (we are used to integer values, but nature does not care about them, like city planners!):

Panorama from DCP 56 ° N 47 ° E (click to view full size)

There are people for whom the awl still works, and even too much - and they invent "home" parallels with the meridians (known to some people as the Hartmann grid), which pass every two meters, and even teach how to correctly position the bed so that do not hit the knots. It takes a psychic to find these lines and nodes. But it's not scary, even I can do it, and even without a frame :). And everyone can, if they try.

Only this is an incident: it is customary to take the same distance between the lines everywhere. I have never heard that the Hartman grid in Murmansk was different from the grid, for example, in Odessa! ;) Apparently, psychics, even graduates, do not always remember the peculiarities of the geometry of the sphere. Meanwhile, you can stretch a square grid of figs over a globe!
But let's leave the glitches of psychics aside and return to geography.
It is easier with the equator and with all meridians: one degree when moving along them is the same everywhere and is approximately 40,000 / 360 = 111 km. And one minute of arc, respectively, is 60 times less: 1.852 km.
By the way, who knows what this number is? My friends, this is a nautical mile! Have you heard about such a unit of distance?

This means that everything is clear with latitude. To get one degree north or south, you have to walk 111 km.
And how much from one meridian to another? At the equator - the same 111 km. And at the pole, obviously, zero! Because there all the meridians converge. And you can commit " trip around the world"around the pole, while crossing all time zones in a few steps!
At our latitude from one meridian to another - only 62 kilometers in the tail.
Therefore, the mysterious points of intersection of parallels and meridians are not so far from us.
And these nodes are called beautifully: confluent points.
Immediately there is a desire to find them and visit. Why, ask? Well, you are not original. Vysotsky has already managed to ask before you:

I asked you: "Why are you going up the hill? -
And you went to the top, and you were eager to fight. -
After all, Elbrus and the plane can be seen great ... "
You laughed and took it with you.

Let's go too. By will strange people ready to travel on virtual lines and their intersections, and the international project Degree Confluence Project was born:

I have already written briefly about those points that are located on the territory of Chuvashia (there are only three of them), c.
I visited one of them as soon as I bought a communicator with GPS. This closest point to us with coordinates 57 ° N 47 ° E is located near the village of Ishlei, on the other side of the village of Khachiki. You can drive close to the point by car both through Ishley and through Khachiki:

The view from the point is shown above, and the visit to the point is described on the DCP website.

We see that there are still many white spots on the territory of Russia (points not visited by DCP users). This does not mean that no one has ever been there, it just means that no one, even if they knew the coordinates, did not bother to tell about it on the DCP project :)
Surprisingly, the lion's share of points in the European part of Russia was "discovered" by the same traveler - Vladimir Chernorutsky. Today he has 131 visited points in 5 countries!

And I must say that points can be in the most remote and inaccessible places - taiga, swamps, or even in the middle of a lake or river. In the latter case, enthusiasts specially take with them inflatable boat and get to the right place already on the water! The nearest point of water is located on the Volga near Zvenigovo:

During the search for my first confluent point, I did not know anything about the Degree Confluence Project, and I safely forgot the note I read about it on Habré. But after visiting I remembered and easily found the corresponding site. It turned out that at this point I was only the third visitor.
But, to my great surprise, on the map of Russia I found a still undiscovered point N57 ° E47 ° in the Kirov region, just 180 km from my house! Well, seven miles is not a hook, as they say.
As well as, I am extremely lucky. I managed to become the discoverer of the point, ahead of the competitor by literally three days!

I was getting ready for a long time, I was almost late. I chose a relatively free day, and drove along the route Cheboksary - Yoshkar-Ola - Sanchursk and another 16 km, through a village with a beautiful name Smetanino (almost to visit Uncle Fedor with Matroskin;)). Unfortunately, the last 35 km of the track (before and after Sanchursk) turned out to be a real off-road rally, suitable only for 4x4 lovers, since there are only memories and asphalt pits left from the road. This part of the journey took almost two hours! Fortunately, the road there has now been repaired, so you can drive safely:

The car had to be left at the nearest point of the road and walk about two kilometers along a swampy, abandoned field to the forest visible on the horizon, where the intersection point is located:

The point itself is located in the forest, fortunately, not very far:

Don't forget your mosquito gear if you want to visit this spot in the summer! I was never able to shoot the planned panorama; hands and face were black under a layer of mosquitoes and horseflies. And here's the point. In the photo at the beginning of the post, you see a mosquito climbing into the lens, and a communicator splattered with fresh blood. So it goes! But we got there:

These are the geographical travels, these are the discoveries. It would seem that interesting? Taiga, horseflies - romance! :)
There are no more undiscovered points nearby, except in the wilds of the Kirov region and no closer than 300-400 km.
But it is not necessary to climb into the taiga beyond the distant lands.
It is possible to organize tourism to the nearest points, what is not a reason? It's time to revive romance!

By the way, one of my colleagues from Togliatti, even before the GPS era, carefully studied the maps and found out that the middle of the Volga is located near Cheboksary!
Hey, city officials! Instead of erecting pretentious monuments with outstretched arms and marking the "zero mile" for tourists on Red Square, it would be better to mark the middle of the Volga. And then you tell where you are from, and you have to clarify that Cheboksary is not where the chebureks and Cheburashka are, but between Gorky and Kazan. But now we can proudly declare: exactly in the center of the Volga!

Big and small trips(cm.

Degree grid consists of a system of lines (parallels and meridians) and their coordinates. In reality, on the earth's surface, these lines are absent. They are carried out on maps and plans for mathematical calculations, determining the location of an object on the surface of the Earth.

Rice. 1. Parallels and meridians

The direction of the meridian coincides with the direction of the shadow at noon. Meridian– conventional line, drawn on the surface of the Earth from one pole to the other. The magnitude of the arc and the circumference of the meridian is measured in degrees. All meridians are equal, intersect at the poles, and have a north-south direction. The length of one degree of each meridian is 111 km (the circumference of the Earth is divided by the number of degrees: 40,000: 360 = 111 km). Knowing this value, it is not difficult to determine the distance along the meridian. For example, the arc length along the meridian is 20 degrees. To find out this length in kilometers, you need 20 x 111 = 2220 km.

Meridians are usually labeled at the top or bottom of the map.

The meridians are counted from the zero meridian (0 degrees) - Greenwich.

Rice. 2. Meridians on the map of Russia

Parallels

Parallel- a conventional line drawn along the Earth's surface parallel to the equator. The direction of the parallel points to the west and east. Parallels are drawn not only parallel to the equator, but also parallel to other parallels, they are different in length and do not intersect.

The longest parallel (40,000 km) is the equator (0 degrees).

Rice. 3. Equator on the map

The length of one degree of each parallel can be seen at the map frame.

Length of 1 degree parallels

Rice. 4. Parallels (a) and meridians (b)

Drawing parallels and meridians. Determining their directions

Parallels and meridians can be drawn through any place on the earth's surface. By the parallels and meridians, you can determine the main and intermediate sides of the horizon. The directions "north", "south" are determined along the meridians, along the parallels - "east", "west". Crossing, parallels and meridians form a degree network.

Bibliography

The main

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

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

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

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

Encyclopedias, dictionaries, reference books and statistical compilations

1. Geography. Modern Illustrated Encyclopedia / A.P. Gorkin. - M .: Rosmen-Press, 2006 .-- 624 p.

Materials on the Internet

1. Federal Institute for Pedagogical Measurements ().

2. Russian Geographical Society ().

In the IV century. BC NS. the greatest thinker of antiquity, Aristotle, proved that our planet has a shape very close to the shape of a ball.

At about the same time, observing the visible movement of the stars and the Sun during travels in various places, the ancient scientists established certain conventional lines for orientation on the earth's surface.

Let's go on a mental journey across the surface of the Earth. The position above the horizon of the imaginary axis of the world, around which the daily rotation of the firmament takes place, will change for us all the time. In accordance with this, the picture of the movement of the starry sky will also change.

Driving north, we see that the stars in the southern sky rise to a lower height every night. And the stars in the northern part - in the lower climax - have a great height. Moving long enough, we get to the North Pole. Here, not a single star rises or falls at all. It will seem to us that the whole sky is slowly spinning parallel to the horizon.

Unbeknownst to ancient travelers, the apparent motion of the stars is a reflection of the rotation of the Earth. And they have not been to the pole. But they needed to have a reference point on the earth's surface. And they chose for this purpose the north-south line, easily identifiable by the stars. This line is called the meridian.

Meridians can be drawn through any point on the Earth's surface. Many meridians form a system of imaginary lines connecting the North and South poles of the Earth, which are convenient to use to determine the location.

Let's take one of the meridians as the initial one. The position of any other meridian in this case will be known if the direction of reference is indicated and dihedral angle between the desired meridian and the initial one.

At present, by international agreement, we have agreed to consider the initial meridian that passes through one of the world's oldest astronomical observatories - the Greenwich Observatory, located on the outskirts of London. The angle formed by any meridian with the initial is called longitude. Longitude, for example, Moscow meridian 37 ° east of Greenwich.

To distinguish points lying on the same meridian from each other, it was necessary to enter a second geographic coordinate - latitude. Latitude is the angle that a plumb line drawn in a given place on the Earth's surface forms with the equatorial plane.

The terms longitude and latitude have come down to us from ancient sailors who described length and breadth Mediterranean Sea... The coordinate that corresponded to the measurements of the length of the Mediterranean Sea became longitude, and the one that corresponded to the width became the modern latitude.

Finding latitude, like determining the direction of the meridian, is closely related to the movement of the stars. Already ancient astronomers proved that the height of the pole of the world above the horizon is exactly equal to the latitude of the place.

Suppose that the Earth has the shape of a regular ball, and we cut it along one of the meridians, as in the figure. Let the person shown in the figure as a light figure stand at the North Pole. For him, the upward direction, that is, the direction of the plumb line, coincides with the axis of the world. The pole of the world is right above his head. The height of the pole of the world is 90 here.

Since the apparent rotation of stars around the axis of the world is a reflection of the real rotation of the Earth, then at any point on the Earth, as we already know, the direction of the axis of the world remains parallel to the direction of the axis of rotation of the Earth. The direction of the plumb line changes from point to point.

Take, for example, another person (in the picture - a dark figure). The direction of the axis of the world for him remained the same as for the first. And the direction of the plumb line has changed. Therefore, the height of the pole of the world above the horizon is not 90 °, but much less.

From simple geometric considerations, it is clear that the height of the pole of the world above the horizon (angle ft in the figure) is indeed equal to latitude (angle φ).

The line connecting points with the same latitude is called a parallel.

Meridians and parallels form the so-called system geographic coordinates... Each point on the earth's surface has a well-defined longitude and latitude. Conversely, if you know the latitude and longitude, then you can build one parallel and one meridian, at the intersection of which you get one single point.

Understanding the features of the diurnal movement of stars and the introduction of a system of geographic coordinates made it possible to carry out the first determination of the Earth's radius. It was completed in the second half of the 3rd century. BC NS. the famous mathematician and geographer Eratosthenes.

The principle of this definition is as follows. Let it be possible to measure the difference in latitudes of two points lying on the same meridian (see Fig.). Thus, we became aware of the angle Δφ with the apex at the center of the Earth, which corresponds to the arc of the meridian L on the Earth's surface. If now it is possible to measure the arc L as well, then we will get a sector with a known arc length and the corresponding central angle. This sector is shown separately in the figure. By simple calculations, you can get the value of the radius of this sector, which is the radius of the Earth.

Eratosthenes, a Greek by nationality, lived in the wealthy Egyptian city of Alexandria. To the south of Alexandria there was another city - Siena, which today is called Aswan and where, as you know, with the help of Soviet Union the famous high-rise dam was built. Eratosthenes knew that Siena possessed interesting feature... At noon on one of the June days, the Sun over Siena is so high that its reflection can be seen at the bottom of even very deep wells. From this Eratosthenes concluded that the height of the Sun in Siena on this day is exactly 90 °. In addition, since Siena lies strictly south of Alexandria, then they are on the same meridian.

For an unusual measurement, Eratosthenes decided to use a scaphis - a cup-shaped sundial with a pin and divisions inside them. Installed vertically, these sundial by the shade of the pin, they make it possible to measure the height of the Sun above the horizon. And at noon on the very day when the Sun rose over Siena so high that all objects ceased to cast shadows. Eratosthenes measured its height in the town square of Alexandria. The height of the Sun in Alexandria, according to the measurements of Eratosthenes, turned out to be 82 ° 48 ". Therefore, the difference in latitudes of Alexandria and Siena is 90 ° 00" - 82 ° 48 "= 7 ° 12".

It remained to measure the distance between them. But how to do that? How to measure on the surface of the Earth a distance equal in modern units to about 800 km?

The difficulties of such an undertaking were then literally incalculable.

Indeed, how to make such a gigantic ruler with which measurements could be made? How to make sure that for 800 km this ruler fits strictly along the meridian, without any distortions?

The necessary data on the distance between the cities had to be taken from the stories of merchants who drove trade caravans from Alexandria to Siena. The merchants said that the distance between them was approximately 5,000 Greek stadia. Eratosthenes accepted this value as true and, using it, calculated the value of the radius of the Earth.

If we compare the value obtained by Eratosthenes with modern data, it turns out that he was mistaken relatively little - only by 100 km.

So, from the III century. BC e., since the time of Eratosthenes, the paths of astronomy and geodesy intertwined - another ancient science, studying the shape and size of the entire Earth as a whole, and its individual parts.

The methods of astronomical determination of latitudes have developed and improved. This was especially important, in particular, precisely in connection with the need for a more thorough determination of the size of the Earth. For, starting with the same Eratosthenes, it was clear that the task of determining the size of the Earth falls into two parts: astronomical, that is, determining the difference in latitudes, and geodesic, that is, determining the length of the meridian arc. Eratosthenes was able to solve the astronomical part of the problem, and in principle the same path followed many of his followers.

We will still have the opportunity to talk about more accurate measurements of the size of the Earth, but for now, having mastered the determination of latitudes, we will deal with a much more complicated matter - the determination of geographical longitudes.

Remember: What is called the equator? What is the length of the earth's equator? What points on Earth are called geographic poles?

Keywords:equator, parallels, meridians, prime meridian, hemisphere, degree grid, geographic position.

1. Parallels. Have you already remembered that e k w a to r is a line conventionally drawn on the earth's surface at the same distance from the poles. He divides Earth to the Northern and Southern Hemispheres (Fig. 42).

Rice. 42. Hemispheres of the Earth. What separates the Western and Eastern, Northern and Southern hemispheres?

Parallels are lines conventionally drawn on the surface of the Earth parallel to the equator. The word "parallel" indicates the position of this line relative to the equator: all points of one parallel are at the same distance from the equator. As you can see on the globe in the form of a parallel - a circle, their length decreases from the equator to the poles. The largest parallel is the equator. The parallel can be drawn through any point on the earth's surface. Each parallel is directed from west to east (Fig. 43).

Rice. 43. Parallels. Rice. 44. Meridians.

Meridians. The shortest lines, conventionally drawn on the surface of the Earth from one pole to another, are called meridians (Fig. 44). The direction of the meridian at any point on the earth's surface is most simply determined through the direction of the shadow from objects at noon. Therefore, the meridian is also called the midday line (Fig. 46). Translated from Latin into Russian, the word "meridian" means "midday line".

Fig. 46. The meridian line coincides with the direction of the shadow from objects at noon.

The meridians indicate the exact direction from north to south. At each point, the meridian is perpendicular to the parallel, which is why they form a right angle with each other (90 °). Therefore, if you face north, that is, in the direction of the meridian, and spread your arms to the sides, they will indicate the direction of the parallel.

Like a parallel, a meridian can be drawn through any point on the earth's surface.

One of the meridians is conventionally considered to be the initial, or zero. According to the international agreement of 1884, the Greenwich meridian, passing through the Greenwich Observatory in London, is considered the initial one. The prime meridian divides the globe into two hemispheres - Western and Eastern (Fig. 42).

3. Degree grid. On the globe and maps, meridians and parallels are drawn through the same number degrees. For example, after 10 0 or 15 0. (Find these symbols on the globe and map). Crossing, parallels and meridians form a degree grid on the globe and maps (Fig. 45).

Rice. 45. Degree grid.

* On a globe, parallels and meridians intersect at right angles. When these angles on the map are greater or less than the right angle, this indicates distortions of angles and directions, and hence the shape of objects. On the globe, all meridians have the same length, and the length of the parallels decreases from the equator to the poles, which corresponds to reality. Violation of this on the map indicates a distortion of distances, and, consequently, areas.

1. What is called a parallel? Meridian? Degree grid? 2. Into which hemispheres does the equator and the prime meridian divide the earth? In which hemispheres is your area located?

3 * Rewrite Table 2 in a notebook and fill it out (write the answer instead of the question).

Table 2.

Degree grid

Degree Grid Line Signs	Meridian	Parallel
1. In which sides of the horizon are they directed?
2. What is the length in degrees?		Decreases from ... to
3. What is the length in kilometers?
4. What is the length of one degree in kilometers?		At each parallel it is different: from 111 km at the equator it decreases towards ...
5. What is the shape of the globe?
5. What is the shape of the hemispheres on the map?

Practical work.

1. Find any meridian on a globe or on a map of hemispheres and determine which continents and oceans it crosses from south to north. 2. Show any parallel and determine which continents and oceans it crosses from west to east.

This video tutorial will be especially useful for those who want to independently get acquainted with the topic "Degree grid". During the lesson, you will be able to determine what the parallel, meridian and degree grid are. The teacher will explain in detail how you can determine the direction by the parallels and meridians on the map.

The direction of the meridian coincides with the direction of the shadow at noon. Meridian- a conditional line drawn on the surface of the Earth from one pole to another. The magnitude of the arc and the circumference of the meridian is measured in degrees. All meridians are equal, intersect at the poles, and have a north-south direction. The length of one degree of each meridian is 111 km (the circumference of the Earth is divided by the number of degrees: 40,000: 360 = 111 km). Knowing this value, it is not difficult to determine the distance along the meridian. For example, the arc length along the meridian is 20 degrees. To find out this length in kilometers, you need 20 x 111 = 2220 km.

Meridians are usually labeled at the top or bottom of the map.

The meridians are counted from the zero meridian (0 degrees) - Greenwich.

Rice. 2. Meridians on the map of Russia

The longest parallel (40,000 km) is the equator (0 degrees).

Rice. 3. Equator on the map ()

The length of one degree of each parallel can be seen at the map frame.

Length of 1 degree parallels ():

Rice. 4. Parallels (a) and meridians (b) ()

Homework

Clause 11.

1. Tell us about the degree grid.