Which parallel is the shortest? What are parallels and meridians in geography? Arctic Circle and Antarctic Circle

The points of intersection of the earth's axis with the surface of the globe are called poles (North and South). The Earth makes one revolution 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 along the surface of the Earth parallel to the equator. The parallels on the map and 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 the ellipsoid into two equal parts (Northern and Southern Hemisphere). With such a dissection, all points of the equator turn out to be equidistant from the poles. The plane of the equator is perpendicular to the Earth's axis of rotation and passes through its center. There are 180 meridians on Earth, 90 of them north of the equator, 90 to the south.

The parallels of 23.5° north and south latitude are called tropical circles or simply the tropics. On each of them, once a year the midday Sun is at its zenith, that is, the sun's rays fall vertically.

The parallels of 66.5° north and south latitude are called the 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 is drawn at the Greenwich Observatory (London, UK). All meridians have the same length and semicircular shape. There are 360 ​​meridians on Earth, 180 to the west of the zero, 180 to the east. The meridians on the map and globe are directed from north to south.

To accurately determine the location of any object on the surface of the earth, one equator line is not enough. Therefore, the hemispheres are mentally separated by many more planes parallel to the equatorial plane - these are parallels. All of them, like the equatorial plane, are perpendicular to the axis of rotation of the planet. You can draw as many parallels as you like, but usually they are drawn with an interval of 10-20°. The 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 greatest, and at the poles it is zero:

Length of parallel arcs

When the globe is crossed by imaginary planes passing through the Earth’s axis perpendicular to the equatorial plane, great circles are formed - meridians. Translated into Russian, the word “meridian” means “noon line”. Indeed, their direction coincides with the direction of the shadow from objects at noon. If you keep walking 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 points on the surface of the Earth. They all intersect at the pole points. 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

The length of all meridians is the same. 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 it always points south.

The image of lines of meridians and parallels on the globe and geographical maps is called a degree grid.

Geographic latitude is the distance of any point on the earth's surface north or south of the equator, expressed in degrees. Latitude is northern (if the point is located north of the equator) and southern (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 prime meridian there will be eastern longitude (abbreviated: E.L.), to the west - western longitude (W.L.).

Geographic coordinates - geographic latitude and geographic longitude of a given object.

Almost all of you have paid attention to the “mysterious lines” on maps and globes representing latitude (parallels) and longitude (meridians). They form a grid coordinate system by which any place on Earth can be precisely located - and there is nothing mysterious or complicated about it. Parallels and meridians are imaginary lines on the surface of the Earth, and latitude and longitude are their coordinates that determine the position of points on the surface of the Earth. Any point on Earth is the intersection of a parallel and a meridian with latitude and longitude coordinates. This can be most clearly studied using a globe, where these lines are marked.
But first things first. Two places on Earth are determined by its rotation around its own axis - these are North and South Poles. On globes, the axis is the rod. The North Pole is located in the Arctic Ocean, which is covered with sea ice, and explorers in the old days reached this pole on sleds with dogs (the North Pole is officially believed to have been discovered in 1909 by the American Robert Perry). However, since the ice moves slowly, the North Pole is not an actual, but rather a mathematical object. The South Pole, on the other side of the planet, has a permanent physical location on the continent of Antarctica, which was also discovered by land explorers (a Norwegian expedition led by Roald Amundsen in 1911).

Halfway between the poles at the “waist” of the Earth there is a large line of a circle, which is represented on the globe as a seam: the junction of the northern and southern hemispheres; this circle line is called - equator. The equator is a line of latitude with a value of zero (0°). Parallel to the equator, above and below it, there are other lines of the circle - these are other latitudes of the Earth. Each latitude has a numerical value, and the scale of these values ​​is measured not in kilometers, but in degrees north and south from the equator to the poles. The poles have the following values: North +90°, and South -90°. Latitudes located above the equator are called northern latitudes, and below the equator - southern latitudes. Lines with degrees of latitude are called parallels, since they run parallel to the Equator and are parallel to each other. If parallels are measured in kilometers, then the lengths of different parallels will be different - they increase as they approach the equator and decrease towards the poles. All points of the same parallel have the same latitude, but different longitude (longitude is described below). The distance between two parallels that differ by 1° is 111.11 km. On the globe, as well as on many maps, the distance (interval) from one latitude to another latitude is usually 15° (this is approximately 1,666 km). In Figure 1, the interval is 10° (this is approximately 1,111 km). The equator is the longest parallel, its length is 40,075.7 km.

If our planet is “cut” through the axis of rotation and perpendicular to it by many planes, then vertical and horizontal circles - meridians and parallels - will appear on the surface.


The meridians will converge at two points - at the North and South Poles. Parallels, as the name suggests, are parallel to each other. Meridians are used to measure longitude, parallels - latitude.

An action so simple at a superficial glance - “ruling out” the Earth - became 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 a single map or a single globe. And they were invented... in the 3rd century BC by the Alexandrian scientist Eratosthenes.

Reference. Eratosthenes had encyclopedic knowledge in all areas at that time. 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 names for lines - parallel and meridian.

Meridian

In geography, a meridian is half a sectional line of the earth's surface drawn through any point on the surface. All imaginary meridians, of which there can be an infinite number, connect 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 ease of movement and mapping, their number and location have been regulated by international treaties. In 1884, at the International Meridian Conference in Washington, it was decided that the prime meridian (zero) would be the one that passes through Greenwich, a county in southeast London.

However, not everyone immediately agreed with this decision. For example, in Russia, even after 1884 until the beginning of the twentieth century, the zero meridian was considered to be its own - Pulkovsky: it “passes” through the Round Hall of the Pulkovo Observatory.

Prime Meridian

The prime meridian is the starting point of geographic longitude. He himself, accordingly, has zero longitude. This was the case before the creation of the world's first satellite navigation system, Transit.


With its appearance, the zero meridian had to be shifted slightly - 5.3″ relative to Greenwich. This is how the International Reference Meridian appeared, which is used as a reference point for longitude by the International Earth Rotation Service.

Parallel

In geography, parallels are lines of an imaginary section of the surface of the planet by planes that are parallel. The parallels depicted on the globe are circles parallel to the equator. They are used to measure geographic latitude.

By analogy with the Greenwich prime meridian, there is also a zero parallel - this is the equator, one of the 5 main parallels, which 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 greater than the speed of sound in air - 331 m/s.

Southern and Northern tropics

The Tropic of the South, also called the Tropic of Capricorn, lies south of the equator and is the latitude above which noon 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, similar to the southern Tropic, represents the latitude above which the midday sun is at its zenith on the day of 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 not visible for the same amount of time.

The Southern Arctic Circle is similar to the Northern Circle in every way, only it is located in the southern hemisphere.

Degree grid

The intersections of meridians and parallels form a degree grid. Meridians and parallels are spaced at intervals of 10° - 20°; smaller divisions, as in angles, are called minutes and seconds.


Using a degree grid, we determine the exact location of geographic objects - their geographic coordinates, calculating longitude using meridians, and latitude using parallels.

Globe is a model of the globe. It clearly shows the location of oceans, continents and other geographical objects. The globe maintains the same scale in all directions, and therefore the image is more accurate than on a map.

The scale must be indicated on a globe or map. It shows the degree to which the sizes of objects and the distances between them are reduced in comparison with the true sizes and distances on the ground. For example, a scale of 1:50,000,000 (one part of fifty million) means that the reduction is 50 million times, that is, 1 cm on a globe or map corresponds to 500 km on the ground.

But globes have a major drawback: they are always on a small scale. If we wanted to make a globe of the same scale as a physical map (1: 5000 000, that is, 1 cm - 50 km), then its diameter would be almost 2.5 m. It is inconvenient to use such a globe.

1. Modern globe. 2. Examples of scales. 3. The surface of the globe, cut into strips along the meridians: distortions are inevitable on a map compiled in this way.

Distances on the globe are determined using a flexible ruler, strip of paper or thread.

On ordinary school globes it is impossible to depict small details in the outlines of continents, in the structure of river networks, mountain ranges, etc. Many states (for example, Denmark, Belgium, Portugal) are depicted with such small figures that there is barely enough space for one circle - symbol of the capital. Therefore, geographic maps are created, on which part of the earth's surface is depicted on a larger scale than on the globe.

If you look at the globe, you can see many thin lines on it. Some run from top to bottom from the North Pole to the South Pole and are called meridians. On the globe and maps they indicate the direction of north and south. Other lines, perpendicular to the meridians, seem to encircle the globe. These are parallels. On maps and the globe they are used to determine the direction to the west and east. The parallels are not equal in length. The longest parallel is the equator, the shortest are located near the poles.

1-2. Meridians and parallels are conventional lines on the globe and map. 3. Degree network. 4. Determination of the directions “north - south” along the meridian. 5. Determination of the directions “west - east” along the parallel.

Both parallels and meridians are conventional lines. They are needed in order to determine the location of geographic objects by geographic coordinates.

Questions and tasks

1. What is a globe?
2. How is it different from a map? Find in the text of the paragraph the answer to the question: what is the main advantage of a globe compared to a geographical map?
3. What is the purpose of indicating scale on a globe and map?
4. Why are parallels and meridians needed?
5. Explain the geographical meaning of the word "orientate".
6. Have you ever wondered what geographical object is located in another hemisphere in a place diametrically opposite to where your city is located? Find it on the globe and describe it according to plan:
   1. what he really is;
   2. what is the name of;
   3. where it is located: in what climatic and time zones it is located, what geographical objects are nearby.
7. Find the intersection of the equator and the prime meridian.
8. Select from the list the characteristic features of parallels:
   1. have the shape of a circle;
   2. carried from pole to pole;
   3. they determine the direction “west - east”;
   4. all the same length.

The need to accurately determine the location of one’s own and surrounding objects on the earth’s surface has become especially important for humans since the beginning of active exploration of the planet.
Geographic coordinates - latitude and longitude - are determined by the intersection point of two imaginary lines - a parallel and a meridian. The longest parallel from which latitude begins is the equator.

origin of name

An imaginary line, which is formed into points located at equal distances from both poles, divides the planet into two hemispheres, two hemispheres. The word for such a border has ancient roots. The Latin "aequator", equalizer, is derived from the verb "aequō" - to equalize. “Equator” came into international practice from the German language, from Äquator.

This word also has a more general meaning. In geometry, a three-dimensional body, which has both an axis and a plane of symmetry mutually perpendicular, has its own equator, its own longest parallel - the intersection of the surface of a given body with the plane of symmetry. In astronomy, the celestial equator and the magnetic equator of a planet or star are known.

The earth is a geoid

The belief that the Earth is shaped like a flat disk was only questioned by ancient Greek scientists. By the end of the 19th century, it became clear that the shape of our planet is not just an ideal sphere, but a special body of rotation - the geoid, the surface of which is influenced by many factors - from the force of gravity to the “cosmic wind”. Two points of the geoid are determined by the axis of its rotation - these are the North and South Pole. At an equal distance from them is the longest parallel on Earth, the earth’s “waist” - the equator.

But the geoid does not accurately, but only approximately describes the shape of the planet. This is how it would be in the absence of mountains and depressions, if there were only a calm, undisturbed surface of the world ocean. This level plays an important role in navigation and geodesy - vertical elevations are reported from it for various technical and engineering objects.

Equator length

You can also understand which parallel is the longest by looking at the specific geometric measurements of the geoid. The radius of the equator, as a circle “drawn” along the surface of the Earth, is equal to the radius of the planet. Precise measurements show that this parameter varies at different points on the planet - the polar radius is 21.3 km less than the equatorial one. Average value - 6371 km

Using the formula for circumference - 2πR - you can calculate the length of the equator. Different geophysical standards define figures with a difference of about 3 m, on average - 40075 km. along the meridian - 40,007 km, which proves the special geometric qualities of the geoid.

Zero latitude

The coordinate grid that covers the globe - a visual model of the globe - is formed by 360 meridians connecting the two poles, and 180 lines parallel to the equator, distributed in 90 pieces to the poles, on both sides of it. The beginning of the longitude count since 1884 is considered to be the meridian drawn through the English capital located in the southeast. The longest parallel dividing the Northern and Southern Hemispheres is the origin of latitude.

Coordinates are angular values ​​measured in degrees. Longitude is the angle between the plane passing through the prime - Greenwich - meridian and the one indicated by the line connecting the earth's poles and drawn through a given point. East of Greenwich to 180° longitude is called eastern and is considered positive, to the west it has negative values ​​and is called western.

Points equidistant from the poles form the equatorial plane. A radius drawn from the center of the globe through a given point on its surface forms an angle with this plane, the magnitude of which is the latitude. The longest parallel has zero latitude. To the north of the equator this angle is considered positive - from 0° to 90°, to the south - negative.

Signs and rituals

The equator is only an illusory border between two hemispheres, but it has always excited the human imagination. It is customary for sailors from different countries to observe special rituals when crossing zero latitude, especially for those who do it for the first time. Where the equator passes through inhabited areas, special signs and structures are invariably erected to make the conventional line real. Rarely will a tourist miss the opportunity to stand with one foot in Yuzhny and the other in Yuzhny. After this, it is impossible to forget what the longest parallel on the globe is called.

But the equatorial zones of the Earth also have other unique characteristics that give them special value. The gravitational attraction here is slightly less than in other latitudes, and the momentum of the rotation of the globe is greater. This allows significant savings for launching spacecraft into orbit. It is no coincidence that the most efficient space launch complex, the Kourou Cosmodrome, is located in equatorial French Guiana, on the South American coast.