Earth makes 11 various movements. Of these, the important geographical significance have daily movement e around the axis and annual circulation around the Sun.
In this case they introduce following definitions:aphelion- the most distant point in orbit from the Sun (152 million km), the Earth passes through it on July 5. Perihelion- the closest point in orbit from the Sun (147 million km), the Earth passes through it on January 3. The total length of the orbit is 940 million km. The farther from the Sun, the lower the speed of movement. Therefore, in the northern hemisphere, winter is shorter than summer. The earth rotates around its axis from west to east, making full turn per day. The rotation axis is constantly inclined to the orbital plane at an angle of 66.5°.
Diurnal movement.
The Earth moves around its axis from west to east , a full revolution is completed in 23 hours 56 minutes 4 seconds. This time is taken as day. At the same time, the Sun seems to rises in the east and moves west. The diurnal movement has 4 consequences :
- compression at the poles and the spherical shape of the Earth;
- the change of night and day;
- the emergence of the Coriolis force - the deflection of horizontally moving bodies in the Northern Hemisphere to the right, in the Southern Hemisphere - to the left, this affects the direction of movement air masses, sea currents etc.;
- the occurrence of ebbs and flows.
Annual revolution of the Earth
Annual revolution of the Earth is the movement of the Earth in an elliptical orbit around the Sun. The earth's axis is inclined to the orbital plane at an angle of 66.5°. When revolving around the Sun, the direction earth's axis does not change - it remains parallel to itself.
Geographical consequence annual rotation The earth is change of seasons , which is also due to the constant tilt of the earth's axis. If the earth's axis were not tilted, then during the year on Earth day would be equal to night, the equatorial regions would receive the most heat, and it would always be cold at the poles. The seasonal rhythm of nature (change of seasons) is manifested in changes in various meteorological elements - air temperature, its humidity, as well as in changes in the regime of water bodies, the life of plants and animals, etc.
The Earth's orbit has several important points corresponding to days equinoxes And solstices.
22nd of June- the day of the summer solstice, when in the Northern Hemisphere it is the longest day and in the Southern Hemisphere the shortest day of the year. On the Arctic Circle and inside it on this day - polar day , on and within the Antarctic Circle - polar night .
December 22- the day of the winter solstice, in the northern hemisphere - the shortest, in the southern hemisphere - the longest day of the year. Within the Northern Arctic Circle - polar night , Southern Arctic Circle - polar day .
21 March And 23 September- the days of the spring and autumn equinoxes, since the rays of the Sun fall vertically on the equator, on the entire Earth (except for the poles) day is equal to night.
The Earth makes a complete revolution around its axis in 23 hours 56 minutes. 4 s. The angular speed of all points on its surface is the same and amounts to 15 degrees / h. Their linear speed depends on the distance that the points must travel during the period of their daily rotation. Points on the equator line rotate at the highest speed (464 m/s). The points that coincide with the North and South Poles remain practically motionless. Thus, the linear speed of points lying on the same meridian decreases from the equator to the poles. Precisely unequal linear speed points on different parallels explains the manifestation of the deflecting action of the Earth's rotation (the so-called Coriolis force) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere relative to the direction of their movement. The deflecting effect especially affects the direction of air masses and sea currents.
The Coriolis force acts only on moving bodies; it is proportional to their mass and speed of movement and depends on the latitude at which the point is located. The more angular velocity, the greater the Coriolis force. The deflecting force of the Earth's rotation increases with latitude. its value can be calculated using the formula
Where m- weight; v- speed of a moving body; w- angular velocity of the Earth's rotation; j- latitude of this point.
The rotation of the Earth causes a rapid cycle of day and night. Daily rotation creates a special rhythm in the development of physical-geographical processes and nature in general. One of the important consequences of the daily rotation of the Earth around its axis is the ebb and flow of tides - a phenomenon periodic oscillation ocean level, which is caused by the gravitational forces of the Sun and Moon. Most of these forces are monthly, and therefore they determine the main features of tidal phenomena. Influx phenomena also occur in earth's crust, but here they do not exceed 30-40 cm, while in the oceans in some cases they reach 13 m (Penzhina Bay) and even 18 m (Bay of Fundy). The height of the water projections on the surface of the oceans is about 20 cm, and they circle the oceans twice a day. Extreme position the water level at the end of the inflow is called high water, at the end of the outflow - low water; the difference between these levels is called the magnitude of the tide.
The mechanism of tidal phenomena is quite complex. Their main essence is that the Earth and the Moon are the only system V rotational movement around general center gravity, which lies inside the Earth at a distance of approximately 4800 km from its center (Fig. 10). Like all flesh, the rotating Earth-Moon system is affected by two forces: gravity and centrifugal force. The ratio of these forces to different sides The earth is not the same. On the side of the Earth facing the Moon, the gravitational forces of the Moon are larger than the centrifugal forces of the system, and their resultant is directed towards the Moon. On the side of the Earth opposite the Moon, the centrifugal forces of the system are larger than the gravitational force of the Moon, and their resultant is directed away from it. These resultants are tidal forces; they cause an increase in water on opposite sides of the Earth.
Rice. 10.
Due to what the Earth does daily rotation in the field of these forces, and the Moon moves around it, the inflow waves try to move in accordance with the position of the Moon, therefore, in each region of the ocean for 24 hours 50 minutes. The tide comes in twice and the tide goes out twice. Daily delay of 50 minutes. due to the advancing movement of the Moon in its orbit around the Earth.
The sun also causes tides on Earth, although they are three times lower in height. They are superimposed on the lunar tides, changing their characteristics.
Despite the fact that the Sun, Earth and Moon are almost in the same plane, they continuously change their mutual arrangement in orbits, therefore their inflow influence changes accordingly. Twice during the monthly cycle - on a new (young) month and a full moon - the Earth, Moon and Sun are on the same line. At this time, the tidal forces of the Moon and the Sun coincide and unusually high, so-called white tides, occur. In the first and third quarters of the Moon, when the tidal forces of the Sun and Moon are directed at right angles to each other, they have opposite influences and heights lunar tides turns out to be less by about one third. These tides are called quadrature.
The problem of using the colossal energy of ebbs and flows has long attracted the attention of mankind, but its solution began with the construction of tidal power plants (TPPs) only now. The first tidal power plant came into operation in France in 1960. In Russia, in 1968, the Kislogubskaya tidal power station was built on the shore of the Kola Bay. Near White Sea, as well as in the Far Eastern seas of Kamchatka, it is planned to build several more TPPs.
The influent waves gradually slow down the speed of the Earth's rotation because they are moving in the opposite direction. Therefore, the earth's day becomes longer. It is calculated that due to water inflows alone, every 40 thousand years the day increases by 1 s. A billion years ago, a day on Earth was only 17 hours long. In a billion years, a day will last 31 hours. And in a few billion years, the Earth will always have one side facing the Moon, just as the Moon is facing the Earth now.
Some scientists believe that the interaction of the Earth with the Moon is one of the main reasons for the initial heating of our planet. The influent friction causes the Moon to move away from the Earth at a speed of about 3 cm/year. This value strongly depends on the distance between the two bodies, which is currently 60.3 Earth radii.
If we assume that at first the Earth and the Moon were much closer, then, on the one hand, the tidal force should be greater. Tidal wave creates internal friction in the body of the planet, which is accompanied by the release of heat,
The Earth's rotation around its axis is associated with its strength, which depends on the angular speed of the planet's daily rotation. Rotation generates centrifugal force, directly proportional to the square of the angular velocity. Now the centrifugal force at the equator, where it is greatest, is only 1/289 of the force gravity. On average, the Earth has a 15-fold safety margin. The Sun is 200 times, and Saturn is only 1.5 times due to its rapid rotation around its axis. Its rings were formed possibly due to the planet's faster rotation in the past. It was hypothesized that the Moon was formed as a result of a separation in the region Pacific Ocean part of the Earth's mass due to its rapid rotation. However, after studying samples of lunar rocks, this hypothesis was rejected, but the fact that the shape of the Earth changes depending on the speed of its rotation does not raise any doubt among experts.
The daily rotation of the Earth is associated with such concepts as sidereal, solar, zone and local time, date line, etc. Time is the basic unit for determining the time during which apparent rotation occurs celestial sphere counterclock-wise. Having noticed the starting point in the sky, the angle of rotation is calculated from it, from which the elapsed time is calculated. Finest hour counted from the moment of the upper culmination of the point spring equinox, where the ecliptic intersects the equator. It is used when astronomical observations. Solar time (present, or true, average) is counted from the moment of the lower culmination of the center of the Sun's disk on the observer's meridian. Local time is average solar time at every point on Earth, which depends on the longitude of that point. The further east a point on Earth is, the longer it has local time (every 15° of longitude gives a time difference of 1 hour), and the further west you go, the shorter the time.
The earth's surface is conventionally divided into 24 time zones, in which time is considered equal to the time of the central meridian, that is, the meridian passing through the middle of the zone.
In densely populated regions, the limits of the belts run along the borders of states and administrative districts, sometimes they coincide with natural boundaries: river beds, mountain ranges etc. In the first time zone the time is one hour more time zero belt, or mean solar time of the Greenwich meridian, in the second zone - at 2:00, etc.
Standard time, which divides the planet into 24 time zones, was introduced in many countries around the world in 1884 p. And although its concentration did not eliminate all misunderstandings related to the calculation of time (let us recall at least the recent heated discussions in some regions of Ukraine regarding the introduction on its territory instead of Moscow Kiev time, that is, the time of a second time zone, in which our country, in fact, located), yet the time zone system has become generally accepted on the planet. After all standard time not only differs little from the local one, it is also convenient for use in distant countries geographic longitude travel. In this regard, it would be appropriate to recall one interesting story, which unexpectedly happened to the participants of the first trip around the world upon its completion.
Late 1522 narrow streets in the Spanish city of Seville there was an unusual procession: 18 sailors from F. Magellan’s expedition had just returned to home harbor after a long ocean voyage. The people were extremely exhausted during the almost three-year voyage. For the first time they walked around globe, accomplished a feat. But the winners were not alike. In hands trembling from weakness, they carried burning candles and slowly headed towards the cathedral to atone for the involuntary sin that they committed during the long voyage...
What were the planet's pioneers guilty of? When Victoria approached the Cape Verde Islands on the way back, a boat was sent ashore for food and fresh water. The sailors soon returned to the ship and informed the amazed crew: for some reason on land this day is considered Thursday, although according to the ship's log it is Wednesday. When returning to Seville, they finally realized that they had lost a day in their ship's account! And this means that we have done great sin because everyone celebrated Religious holidays a day earlier than the calendar required. They repented of this in the cathedral.
How did experienced sailors lose a day? It must be said right away that they did not make any mistake in counting the days. The fact is that the globe rotates around its axis from west to east and every other day makes one revolution. The expedition of F. Magellan moved in the opposite direction from east to west and from three years of traveling around the world, she also made a full revolution around the earth's axis, but in the direction opposite direction rotation of the Earth, which means that the travelers made one revolution less than all of humanity on Earth. And they didn’t lose a day, but won it. If the expedition had moved not to the west, but to the east, then the ship’s log would have recorded one day more than all the people. The astronomer of F. Magellan's expedition, Antonio Pigafetta, guessed that in different places the globe at the same moment at different times. And this is how it should be, because the Sun does not rise at the same time for the entire planet. This means that on each meridian there is local time, the beginning of which is counted from the moment when the Sun is low below the horizon, that is, at the so-called lower culmination. However, people in their daily activities do not pay attention to this and focus on the standard time corresponding to the local time of the median meridian of the corresponding time zone.
But dividing the globe into time zones still does not solve all problems, in particular the problem rational use light period. Therefore, on the last Sunday of March in many countries, including Ukraine, the clock hands are moved forward one hour, and at the end of October they are returned to standard time. Go to summer time allows for more economical use of fuel and energy resources. In addition, this gives people the opportunity to work and relax more in natural light, and to use the darkest time of day for sleep.
IN practical distribution Time zones on our planet are specific spaces through which the international date line conventionally passes. This line runs mainly in open ocean along the geographical meridian 180 ° and deviates slightly where it crosses islands or separates various states. This was done to avoid certain calendar inconveniences for the people who inhabit them. When crossing a line from west to east, the date is repeated; when moving in reverse direction one day is excluded from the account. Interestingly, in the Bering Strait between Chukotka and Alaska there are two islands that are separated by the International Date Line: Ratmanov Island, which belongs to Russia, and Kruzenshtern Island, which belongs to SELA. Having covered a distance of several kilometers between two islands, you can find yourself... in yesterday, if you are sailing from Ratmanov Island, or in tomorrow, when heading in the opposite direction.
Our planet is in constant movement, it revolves around the Sun and own axis. The Earth's axis is an imaginary line drawn from the North to the South Pole (they remain motionless during rotation) at an angle of 66 0 33 ꞌ relative to the plane of the Earth. People cannot notice the moment of rotation, because all objects move in parallel, their speed is the same. It would look exactly the same as if we were sailing on a ship and did not notice the movement of objects and objects on it.
A full revolution around the axis is completed within one sidereal day, consisting of 23 hours 56 minutes and 4 seconds. During this period, first one or the other side of the planet turns towards the Sun, receiving from it different quantity warmth and light. In addition, the rotation of the Earth around its axis affects its shape (flattened poles are the result of the planet’s rotation around its axis) and the deviation when bodies move in the horizontal plane (rivers, currents and winds of the Southern Hemisphere deviate to the left, of the Northern Hemisphere to the right).
Linear and angular rotation speed
(Earth Rotation)
The linear speed of rotation of the Earth around its axis is 465 m/s or 1674 km/h in the equator zone; as you move away from it, the speed gradually slows down, in the North and South Poles it is equal to zero. For example, for citizens of the equatorial city of Quito (the capital of Ecuador in South America) the rotation speed is just 465 m/s, and for Muscovites living on the 55th parallel north of the equator, it is 260 m/s (almost half as much).
Every year, the speed of rotation around the axis decreases by 4 milliseconds, which is due to the influence of the Moon on the strength of sea and ocean tides. The Moon's gravity pulls water in the opposite direction to axial rotation Earth, forming a slight frictional force that slows down the rotation speed by 4 milliseconds. Speed angular rotation remains the same everywhere, its value is 15 degrees per hour.
Why does day give way to night?
(The change of night and day)
The time for a complete revolution of the Earth around its axis is one sidereal day (23 hours 56 minutes 4 seconds), during this time period the side illuminated by the Sun is first “in the power” of the day, the shadow side is under the control of the night, and then vice versa.
If the Earth rotated differently and one side of it was constantly turned towards the Sun, then there would be heat(up to 100 degrees Celsius) and all the water would have evaporated; on the other side, on the contrary, frosts would have raged and the water would have been under a thick layer of ice. Both the first and second conditions would be unacceptable for the development of life and the existence of the human species.
Why do the seasons change?
(Change of seasons on Earth)
Due to the fact that the axis is tilted relative to earth's surface at a certain angle, its sections receive different time varying amounts of heat and light, which causes the seasons to change. According to the astronomical parameters necessary to determine the time of year, certain points in time are taken as reference points: for summer and winter these are the Solstice Days (June 21 and December 22), for spring and autumn - the Equinoxes (March 20 and September 23). From September to March North hemisphere turned towards the Sun for less time and accordingly receives less heat and light, hello winter-winter, the Southern Hemisphere receives a lot of heat and light at this time, long live summer! 6 months pass and the Earth moves to the opposite point its orbit and the Northern Hemisphere receives more heat and light, the days become longer, the Sun rises higher - summer comes.
If the Earth were located in relation to the Sun in an exclusively vertical position, then the seasons would not exist at all, because all points on the half illuminated by the Sun would receive the same and uniform amount of heat and light.
Remember! What is the Earth's orbit called? What hemispheres does the equator divide the Earth into?
Every day the Sun rises in the morning, at noon it stands high in the sky, and in the evening it disappears behind the horizon and night falls. Why is this happening?
Think! Or can the Sun simultaneously illuminate the entire Earth? Why? Can they Sun rays go through the Earth or go around it? Why?
Rice. 13. Rotation of the Earth around its axis
Earth - opaque cosmic body, which moves around its axis from west to east. When one side of the Earth is turned towards the Sun and illuminated by its rays, then the opposite side at this time is in the shade. On the illuminated side it is day, on the unlit side it is night. The Earth makes a full revolution around its axis in one day, which lasts 24 hours. Consequently, the rotation of the Earth around its axis causes the cycle of day and night.
While rotating around its axis, the Earth simultaneously moves in orbit around the Sun.
It is important that the imaginary axis of the Earth is always located under same angle. While moving around the Sun, our planet returns more to it either in the Southern or Northern hemisphere. When the Northern Hemisphere is turned towards the Sun, it receives a lot of light and heat, and summer reigns there. IN Southern Hemisphere It's winter at this time.
Rice. 14. The annual movement of the Earth around the Sun
The earth is constantly moving. Gradually, it turns more and more towards the Sun with the Southern Hemisphere and turns away from it with the Northern Hemisphere. Where there was summer, autumn comes, and in the Southern Hemisphere after cold winter spring is coming.
Continuing to move, after some time the Earth turns towards the Sun so that the Northern Hemisphere is illuminated and warmed even less, and the Southern Hemisphere even more. Then winter begins in the Northern Hemisphere, and summer begins in the Southern Hemisphere.
Subsequently, the Earth begins to return to the Sun again by the Northern Hemisphere. It gets warmer and spring comes, and autumn comes to the Southern Hemisphere.
So, the Northern and Southern hemispheres of the Earth, during its rotation around the Sun, simultaneously receive unequal amounts of sunlight and warmth, which causes the change of seasons.
The Earth makes a full revolution around the Sun in one year, which lasts 365 days 5 hours 48 minutes 46 seconds. This number is rounded and 365 days are written on the calendar for three years. Over 4 years, 5 hours with minutes and seconds are added, and another era is obtained. Therefore, every fourth year February 29 appears in the calendar. A year with a duration of 366 days is called a leap year.
Discuss! What would happen on Earth if the axis were not tilted?
Leap year.
Test your knowledge
1. Why does the change of day and night occur on Earth?
2. What is a day? How long does it last?
3. Why do seasons change on Earth?
4. How long does a typical earthly year last? What about leap year?
5. According to Dima, if the Sun illuminates the Northern Hemisphere more, then spring comes on its territory. Is the boy right? Explain why.
Let's sum it up together
The Earth simultaneously carries out daily and annual movement. The change of day and night is a consequence of its rotation around its axis, which lasts 24 hours - a day. A year is the period of time during which the Earth makes a complete revolution around the Sun. It lasts approximately 365 days. The movement of the Earth around the Sun causes the seasons to change.
A highlight for the curious
The earth moves around its axis at a certain speed. It is greatest at the equator and amounts to 464 m/sec. average speed The movement of the Earth around the Sun is 30 km/sec.
Hello dear readers! Today I would like to touch on the topic of the Earth and, and I thought that a post about how the Earth rotates would be useful to you 🙂 After all, day and night, and also the seasons, depend on this. Let's take a closer look at everything.
Our planet rotates around its axis and around the Sun. When it makes one revolution around its axis, one day passes, and when it revolves around the Sun, one year passes. Read more about this below:
Earth's axis.
Earth's axis (Earth's rotation axis) – this is the straight line around which the Earth’s daily rotation occurs; this line passes through the center and intersects the surface of the Earth.
The tilt of the Earth's rotation axis.
The Earth's rotation axis is inclined to the plane at an angle of 66°33´; thanks to this it happens. When the Sun is above the Tropic of the North (23°27´ N), summer begins in the Northern Hemisphere, and the Earth is at its farthest distance from the Sun.
When the Sun rises above the Tropic of South (23°27´ S), summer begins in the Southern Hemisphere.
In the Northern Hemisphere, winter begins at this time. The attraction of the Moon, Sun and other planets does not change the angle of inclination of the earth's axis, but causes it to move along circular cone. This movement is called precession.
The North Pole now points toward the North Star. Over the next 12,000 years, as a result of precession, the Earth's axis will travel approximately halfway and will be directed towards the star Vega.
About 25,800 years old full cycle precession and significantly influences the climate cycle.
Twice a year, when the Sun is directly above the equator, and twice a month, when the Moon is in a similar position, the attraction due to precession decreases to zero and periodic increase and a decrease in the rate of precession.
Such oscillatory movements Earth's axis is known as nutation, which reaches a maximum every 18.6 years. In terms of the significance of its influence on climate, this periodicity ranks second after changes in seasons.
The rotation of the Earth around its axis.
Daily rotation of the Earth - the movement of the Earth counterclockwise, or from west to east, when viewed from North Pole peace. The rotation of the Earth determines the length of the day and causes the change between day and night.
The Earth makes one revolution around its axis in 23 hours 56 minutes and 4.09 seconds. During the period of one revolution around the Sun, the Earth approximately makes 365 ¼ revolutions, this is one year or equal to 365 ¼ days.
Every four years, another day is added to the calendar, because for each such revolution, in addition to a whole day, another quarter of a day is spent. The Earth's rotation is gradually slowing down gravitational attraction Moon, and extends the day by approximately 1/1000 s every century.
Judging by geological data, the rate of rotation of the Earth could change, but not by more than 5%.
Around the Sun, the Earth rotates in an elliptical orbit, close to circular, at a speed of about 107,000 km/h in the direction from west to east. The average distance to the Sun is 149,598 thousand km, and the difference between the smallest and the largest long distance 4.8 million km.
Eccentricity (deviation from the circle) earth's orbit changes slightly over a cycle lasting 94 thousand years. It is believed that the formation of a complex climate cycle is facilitated by changes in the distance to the Sun, and the advance and departure of glaciers during ice ages are associated with its individual stages.
Everything is in our vast universe It is very complex and precise. And our Earth is just a point in it, but it is ours native home, which we learned a little more about in the post about how the Earth rotates. See you in new posts about the study of the Earth and the Universe🙂