The Earth makes a complete revolution around the Sun in 365 days and 6 hours. For convenience, it is customary to assume that there are 365 days in a year. And every four years, when the extra 24 hours “accumulate”, a leap year begins, in which there are not 365, but 366 days (29 in February).

In September, when you return to school after the summer holidays, autumn comes. The days are getting shorter and the nights are longer and cooler. In a month or two, leaves will fall from the trees, migratory birds will fly away, and the first snowflakes will swirl in the air. In December, when the snow covers the earth with a white veil, winter will come. The shortest days of the year are coming. The sunrise at this time is late and the sunset is early.

In March, when spring comes, the days lengthen, the sun shines brighter, the air becomes warmer, streams begin to murmur all around. Nature comes to life again, and soon the long-awaited summer begins.

So it has been and will always be from year to year. Have you ever wondered why the seasons change?

Geographic Consequences of the Earth's Movement

You already know that the Earth has two main movements: it rotates on its axis and orbits around the Sun. In this case, the earth's axis is inclined to the plane of the orbit by 66.5 °. The movement of the Earth around the Sun and the tilt of the earth's axis determine the change of seasons and the length of day and night on our planet.

Twice a year, in spring and autumn, there come days when the length of the day on the whole Earth is equal to the length of the night - 12 hours. The day of the spring equinox comes on March 21-22, the day of the autumn equinox on September 22-23. At the equator, day is always equal to night.

The longest day and the shortest night on Earth occur in the Northern Hemisphere on June 22, and in the Southern Hemisphere on December 22. These are the summer solstice.

After June 22, due to the movement of the Earth in orbit, in the Northern Hemisphere, the height of the Sun above gradually decreases, the days become shorter, and the nights become longer. And in the Southern Hemisphere, the Sun rises higher above the horizon and daylight hours increase. The southern hemisphere receives more and more solar heat, while the northern hemisphere receives less and less.

The shortest day in the Northern Hemisphere is on December 22, and in the Southern Hemisphere on June 22. This is the winter solstice.

At the equator, the angle of incidence of the sun's rays on the earth's surface and the length of the day change little, so it is almost impossible to notice the change of seasons there.

On some features of the motion of our planet

There are two parallels on Earth, on which the Sun at noon on the days of the summer and winter solstices is at its zenith, that is, it stands directly above the observer's head. Such parallels are called tropics. On the Northern Tropic (23.5 ° N), the Sun is at its zenith on June 22, on the Southern Tropic (23.5 ° S) - on December 22.

The parallels located at 66.5° north and south latitude are called the polar circles. They are considered the boundaries of territories where polar days and polar nights are observed. The polar day is the period when the Sun does not fall below the horizon. The closer from the Arctic Circle to the Pole, the longer the polar day. At the latitude of the Arctic Circle, it lasts only one day, and at the pole - 189 days. In the Northern Hemisphere at the latitude of the Arctic Circle, the polar day begins on June 22 on the day of the summer solstice, and in the Southern Hemisphere - on December 22. The duration of the polar night varies from one day (at the latitude of the polar circles) to 176 (at the poles). All this time the Sun does not appear above the horizon. In the Northern Hemisphere, this natural phenomenon begins on December 22, and in the Southern Hemisphere on June 22.

It is impossible not to note that wonderful period at the beginning of summer, when the evening dawn converges with the morning and twilight, white nights last all night. They are observed in both hemispheres at latitudes exceeding 60, when the Sun at midnight falls below the horizon by no more than 7 °. In (about 60° N) white nights last from June 11 to July 2, and in Arkhangelsk (64° N) from May 13 to July 30.

Light belts

The consequence of the annual movement of the Earth and its daily rotation is the uneven distribution of sunlight and heat over the earth's surface. Therefore, there are belts of illumination on Earth.

Between the Northern and Southern tropics on both sides of the equator lies the tropical belt of illumination. It occupies 40% of the earth's surface, which accounts for the largest amount of sunlight. Between the tropics and the polar circles in the southern and northern hemispheres are temperate light zones that receive less sunlight than the tropical zone. From the Arctic Circle to the Pole, each hemisphere has polar belts. This part of the earth's surface receives the least amount of sunlight. Unlike other belts of illumination, only here there are polar days and nights.

The Earth makes a complete revolution around the Sun in 365 days 6 hours 9 minutes and 9 seconds. On March 21 and September 23, the inclination of the earth's axis is neutral with respect to the Sun (equinox days). On June 21, the Earth occupies a position in which its axis at its northern end on December 22, on the day of the winter solstice, the sheer rays fall on the southern tropic, and the northern polar countries , starting from the Arctic Circle, are not illuminated. In the Antarctic Circle and further to the pole, the Sun is above the horizon around the clock. This continues until the spring equinox - March 21.

Lighting belts

There are 13 lighting zones in total. The equatorial belt is located on both sides of the equator. day and night are almost always equal here, twilight is very short, there is no change of seasons. Tropical zones: the length of day and night varies from 10.5 to 13.5 hours; twilight is short, there are two seasons of the year that differ little in temperature. Subtropical belts: The length of day and night for extreme latitudes ranges from 9 hours to 14 hours. Twilight is short, winter and summer are often pronounced, spring and autumn are less pronounced. Temperate zones: All four seasons are clearly expressed (spring, summer, autumn, winter). Winter and summer are approximately equal. Belts of summer nights and short winter days: all four seasons are expressed, winter is longer than summer. subpolar belts. Polar belts: the seasons coincide with day and night.

The motion of the binary planet Earth-Moon and tidal friction

Universal gravitation is balanced by universal repulsion. The essence of gravitation (gravity) is that all bodies are attracted to each other in proportion to their masses and inversely proportional to the square of the distance between them. Repulsion is a centrifugal force that occurs during the rotation and circulation of celestial bodies. The Earth and the Moon are mutually attracted, but the Moon cannot fall to the Earth, since it revolves around the Earth and thus tends to get away from it. The balance of attraction and repulsion is true for the centers of the planets. However, it does not apply to individual points on the Earth's surface. So there are ebbs and flows. The interaction of two forces - the force of attraction and the centrifugal force - is the tide-forming force. The tides are best expressed in the oceans.

ATMOSPHERE

The atmosphere is the gaseous envelope of the Earth. At present, the atmosphere consists of the following components: Nitrogen - 78.08%, Oxygen - 20.94%, Argon - 0.93%, Carbon dioxide - 0.03%, Other gases - 0.02%. The atmosphere consists of the following layers: troposphere, stratosphere, mesosphere, thermosphere and exosphere. The geographic envelope includes only the troposphere and the lower part of the stratosphere. The average thickness of the troposphere is about 11 km. Above the troposphere is the tropopause, which is a thin transitional layer with a thickness of about one kilometer. Above the tropopause is the stratosphere. The stratosphere begins 8 km above the poles and 16-18 km above the equator. Above the heated layer of the upper atmosphere, after the stratopause, i.e., above 55 km, lies the mesosphere, which extends to a height of 80 km. In it, the temperature again drops to -90 0C. At altitudes from 80 to 90 km there is a mesopause with a constant temperature of about 1800 C. Above the mesopause is the thermosphere, which extends up to 800 - 1000 km. Above 1,000 km, the outer atmosphere, or exosphere, begins, extending up to 2,000–3,000 km. The troposphere and lower stratosphere are called the lower atmosphere, and all higher layers are called the upper atmosphere.

Solar radiation

Solar radiation is the totality of solar matter and energy entering the Earth. Solar radiation carries light and heat. The intensity of solar radiation must be measured primarily outside the atmosphere, because when passing through the air sphere, it is transformed and weakens. The intensity of solar radiation is expressed by the solar constant. The solar constant is the flux of solar energy in 1 minute over an area with a cross section of 1 cm2, perpendicular to the sun's rays and located outside the atmosphere. The solar constant, contrary to its name, does not remain constant. It changes due to the change in the distance from the Sun to the Earth as the Earth moves in its orbit. No matter how small these fluctuations are, they always affect the weather and climate.

Visible movement of the firmament. It is known that the heavenly bodies are located at various distances from the globe. At the same time, it seems to us that the distances to the luminaries are the same and they are all connected with one spherical surface, which we call the firmament, and astronomers call the visible celestial sphere. It seems to us so because the distances to the heavenly bodies are very large, and our eye is not able to notice the difference in these distances. Each observer can easily notice that the visible celestial sphere with all the luminaries located on it slowly rotates. This phenomenon was well known to people from ancient times, and they took the apparent movement of the Sun, planets and stars around the Earth as real. At present, we know that it is not the Sun and stars that move around the Earth, but the globe rotates.

Accurate observations have shown that the complete rotation of the Earth around its axis takes place at 23 hours 56 minutes. and 4 sec. We take the time of a complete revolution of the Earth around its axis as a day, and for simplicity, we consider 24 hours in a day.

Evidence for the rotation of the earth on its axis. We now have a number of very compelling evidence for the rotation of the earth. Let us dwell first of all on the proofs arising from physics.

Foucault experience. In Leningrad, in the former St. Isaac's Cathedral, a pendulum is suspended, having 98 m length, with a load of 50 kg. Below the pendulum is a large circle divided into degrees. When the pendulum is at rest, its weight is located just in the center of the circle. If we take the weight of the pendulum to the zero degree of the circle, and then let it go, then the pendulum will swing in the plane of the meridian, that is, from north to south. However, already after 15 minutes the swing plane of the pendulum will deviate by about 4°, after an hour by 15°, etc. It is known from physics that the swing plane of the pendulum cannot deviate. Consequently, the position of the graduated circle changed, which could only happen as a result of the daily movement of the Earth.

To more clearly imagine the essence of the matter, let's turn to the drawing (Fig. 13, a), which shows the northern hemisphere in a polar projection

The meridians extending from the pole are indicated by a dotted line. The small circles on the meridians are a conventional image of a graduated circle under the pendulum of St. Isaac's Cathedral. At the first position ( AB) the plane of the pendulum's swing (indicated by the solid line in the circle) completely coincides with the plane of the given meridian. After a while the meridian AB due to the rotation of the earth from west to east will be in position A 1 B 1 . The plane of swing of the pendulum remains the same, which is why the angle between the plane of swing of the pendulum and the plane of the meridian is obtained. With further rotation of the Earth, the meridian AB will be in position A 2 B 2 etc. It is clear that the plane of swing of the pendulum will deviate even more from the plane of the meridian AB. If the Earth was stationary, such a discrepancy could not have happened, and the pendulum would have swung from beginning to end in the direction of the meridian.

A similar experiment (on a smaller scale) was first made in Paris in 1851 by the physicist Foucault, which is why it got its name.

Experiment with deflection of falling bodies to the east. According to the laws of physics, the load must fall from a height along a plumb line. However, in all experiments performed, the falling body invariably deviated to the east. The deviation occurs because during the rotation of the Earth, the speed of the body from west to east at a height is greater than at the level of the earth's surface. The latter can be easily understood from the attached drawing (Fig. 13, b). A point located on the earth's surface moves along with the Earth from west to east and, in a certain period of time, travels a path BB 1 . A point located at a certain height, for the same period of time, makes a path AA 1 . Body thrown from a point BUT, moving at a height faster than a point AT, and during the time the body falls, point BUT will move to point A 1 and a body with a high speed will fall east of point B 1 . According to the experiments carried out, a body falling from a height of 85 m deviated from the plumb line to the east by 1.04 mm, and when falling from a height of 158.5 m- by 2.75 cm.

The rotation of the Earth is also indicated by the oblateness of the globe at the poles, the deviation of winds and currents in the northern hemisphere to the right, and in the southern hemisphere - to the left, which will be discussed in more detail later.

The rotation of the Earth makes it clear to us why the polar oblateness of the Earth does not cause the water masses of the oceans to move from the equator to the poles, i.e., to a position closest to the center of the Earth (centrifugal force keeps these waters from moving to the poles), etc.

The geographical significance of the daily rotationearth. The first consequence of the rotation of the Earth on its axis is the change of day and night. This change is quite fast, which is very important for the development of life on Earth. Owing to the shortness of day and night, the earth can neither be overheated nor supercooled to such an extent that life would be killed either by excessive heat or excessive cold.

The change of day and night determines the rhythm of many processes on Earth associated with the arrival and consumption of heat.

The second consequence of the rotation of the Earth around its axis is the deviation of any moving body from its original direction in the northern hemisphere to the right, and in the southern hemisphere to the left, which is of great importance in the life of the Earth. We cannot give a complex mathematical proof of this law here, but we will try to give some, though very simplified, explanation.

Suppose that the body has received a rectilinear motion from the equator to the North Pole. If the Earth did not rotate around its axis, then the moving body in. in the end it would be at the pole. However, this does not happen on Earth because the body, being at the equator, moves along with the Earth from west to east (Fig. 14, a). Moving towards the pole, the body passes into more

high latitudes, where every point on the earth's surface moves from west to east more slowly than at the equator. A body moving towards the pole, according to the law of inertia, retains the same speed of movement from west to east that it had at the equator. As a result, the path of the body will always deviate from the direction of the meridian to the right. It is easy to understand that in the southern hemisphere, under the same conditions of motion, the path of the body will deviate to the left (Fig. 14.6).

Poles, equator, parallels and meridians. Thanks to the same rotation of the Earth around its axis, we have two wonderful points on Earth, which are called poles. The poles are the only fixed points on the earth's surface. Based on the poles, we determine the location of the equator, draw parallels and meridians and create a coordinate system that allows us to determine the position of any point on the surface of the globe. The latter, in turn, gives us the opportunity to plot all geographical objects on maps.

A circle formed by a plane perpendicular to the earth's axis, and dividing the globe into two equal hemispheres, is called equator. The circle formed by the intersection of the equatorial plane with the surface of the globe is called the equatorial line. But in colloquial speech and geographical literature, the line of the equator is often called simply the equator for brevity.

The globe can be mentally crossed by planes parallel to the equator. In this case, circles are obtained, which are called parallels. It is clear that the dimensions of the parallels for the same hemisphere are not the same: they decrease with distance from the equator. The direction of the parallel on the earth's surface is the exact direction from east to west.

The globe can be mentally dissected by planes passing through the earth's axis. These planes are called meridian planes. The circles formed by the intersection of meridian planes with the surface of the globe are called meridians. Every meridian inevitably passes through both poles. In other words, the meridian everywhere has an exact direction from north to south. The direction of the meridian at any point on the earth's surface is most simply determined by the direction of the midday shadow, which is why the meridian is also called the midday line (lat. rneridlanus, which means midday).

Latitude and longitude. The distance from the equator to each of the poles is a quarter of a circle, i.e. 90 °. Degrees are counted along the meridian line from the equator (0°) to the poles (90°). The distance from the equator to the North Pole, expressed in degrees, is called north latitude, and to the South Pole - south latitude. Instead of the word latitude, for brevity, they often write the sign φ (the Greek letter "phi", northern latitude with a + sign, southern latitude with a - sign), for example, φ \u003d + 35 ° 40 ".

When determining the degree distance to the east or west, the calculation is carried out from one of the meridians, which is conventionally considered to be zero. By international agreement, the prime meridian is the meridian of the Greenwich Observatory, located on the outskirts of London. The degree distance to the east (from 0 to 180 °) is called eastern longitude, and to the west - western longitude. Instead of the word longitude, they often write the sign λ (the Greek letter "lambda", eastern longitude with a + sign, and western longitude with a - sign), for example, λ = -24 ° 30 / . Using latitude and longitude, we have the ability to determine the position of any point on the earth's surface.

Determination of latitude on Earth. Determining the latitude of a place on Earth is reduced to determining the height of the celestial pole above the horizon, which can be easily seen from the drawing (Fig. 15). The easiest way to do this in our hemisphere is with the help of the North Star, which is located only 1 o 02 "from the celestial pole.

An observer at the North Pole sees the North Star just overhead. In other words, the angle formed by the ray of the North Star and the plane of the horizon is 90 °, that is, it just corresponds to the latitude of the given place. For an observer located at the equator, the angle formed by the ray of the North Star and the plane of the horizon should be 0 °, which again corresponds to the latitude of the place. When moving from the equator to the pole, this angle will increase from 0 to 90 ° and will always correspond to the latitude of the place (Fig. 16).

It is much more difficult to determine the latitude of a place from other luminaries. Here you have to first determine the height of the luminary above the horizon (i.e., the angle formed by the ray of this luminary and the plane of the horizon), then calculate the upper and lower culmination of the luminary (its position at 12 o'clock in the afternoon and 0 o'clock in the night) and take the arithmetic average between them. Calculations of this kind require special rather complex tables.

The simplest instrument for determining the height of a star above the horizon is the theodolite (Fig. 17). At sea, in conditions of rolling, a more convenient sextant device is used (Fig. 18).

The sextant consists of a frame, which is a sector of a circle of 60 °, i.e., constituting 1/6 of the circle (hence the name from the Latin sextans- sixth part). A small spotting scope is fixed on one spoke (frame). On the other needle - a mirror BUT, half of which is covered with amalgam and the other half is transparent. Second mirror AT attached to the alidade, which serves to measure the angles of the graduated limbus. The observer looks through the telescope (point O) and sees through the transparent part of the mirror BUT horizon I. Moving the alidade, he catches on the mirror BUT image of a luminary S, reflected from the mirror AT. From the attached drawing (Fig. 18) it can be seen that the angle SOH (determining the height of the luminary above the horizon) is equal to the double angle CBN.

Determining longitude on earth. It is known that each meridian has its own so-called local time, and a difference of 1° of longitude corresponds to 4 minutes of time difference. (A full rotation of the Earth around its axis (360 °) takes 24 hours, and a rotation of 1 ° \u003d 24 hours: 360 °, or 1440 minutes: 360 ° \u003d 4 minutes.) It is easy to see that the difference in time between two points easily allows you to calculate the difference in longitudes. For example, if in this paragraph 13 hours. 2 minutes, and on the zero meridian 12 hours, then the time difference = 1 hour. 2 minutes, or 62 minutes, and the difference in degrees is 62:4 = 15°30 / . Therefore, the longitude of our point is 15 ° 30 / . Thus, the principle of calculating longitudes is very simple. As for methods for accurately determining longitude, they present considerable difficulties. The first difficulty is the exact determination of local time by astronomical means. The second difficulty is the need

to have accurate chronometers. In recent times, thanks to radio, the second difficulty has been greatly eased, but the first remains in force.

Our planet is in constant motion. Together with the Sun, it moves in space around the center of the Galaxy. And that, in turn, moves in the universe. But the most important thing for all living things is the rotation of the Earth around the Sun and its own axis. Without this movement, the conditions on the planet would be unsuitable for sustaining life.

solar system

Earth as a planet of the solar system, according to scientists, was formed more than 4.5 billion years ago. During this time, the distance from the sun practically did not change. The speed of the planet and the gravitational pull of the sun balance its orbit. It is not perfectly round, but stable. If the force of attraction of the star were stronger or the speed of the Earth decreased noticeably, then it would fall on the Sun. Otherwise, sooner or later it would fly into space, ceasing to be part of the system.

The distance from the Sun to the Earth makes it possible to maintain the optimum temperature on its surface. The atmosphere also plays an important role in this. As the Earth rotates around the Sun, the seasons change. Nature has adapted to such cycles. But if our planet were further away, then the temperature on it would become negative. If it were closer, all the water would evaporate, since the thermometer would exceed the boiling point.

The path of a planet around a star is called an orbit. The trajectory of this flight is not perfectly round. It has an ellipse. The maximum difference is 5 million km. The closest point of the orbit to the Sun is at a distance of 147 km. It's called perihelion. Its land passes in January. In July, the planet is at its maximum distance from the star. The greatest distance is 152 million km. This point is called aphelion.

The rotation of the Earth around its axis and the Sun provides, respectively, a change in daily regimes and annual periods.

For a person, the movement of the planet around the center of the system is imperceptible. This is because the mass of the Earth is enormous. Nevertheless, every second we fly through space about 30 km. It seems unrealistic, but such are the calculations. On average, it is believed that the Earth is located at a distance of about 150 million km from the Sun. It makes one complete revolution around the star in 365 days. The distance traveled in a year is almost a billion kilometers.

The exact distance that our planet travels in a year, moving around the sun, is 942 million km. Together with her, we move in space in an elliptical orbit at a speed of 107,000 km / h. The direction of rotation is from west to east, that is, counterclockwise.

The planet does not complete a complete revolution in exactly 365 days, as is commonly believed. It still takes about six hours. But for the convenience of chronology, this time is taken into account in total for 4 years. As a result, one additional day “runs in”, it is added in February. Such a year is considered a leap year.

The speed of rotation of the Earth around the Sun is not constant. It has deviations from the mean. This is due to the elliptical orbit. The difference between the values ​​is most pronounced at the points of perihelion and aphelion and is 1 km/sec. These changes are imperceptible, since we and all the objects around us move in the same coordinate system.

change of seasons

The rotation of the Earth around the Sun and the tilt of the planet's axis make it possible for the seasons to change. It is less noticeable at the equator. But closer to the poles, the annual cyclicity is more pronounced. The northern and southern hemispheres of the planet are heated by the energy of the Sun unevenly.

Moving around the star, they pass four conditional points of the orbit. At the same time, twice in turn during the semi-annual cycle, they turn out to be further or closer to it (in December and June - the days of the solstices). Accordingly, in a place where the surface of the planet warms up better, the ambient temperature is higher there. The period in such a territory is usually called summer. In the other hemisphere at this time it is noticeably colder - it is winter there.

After three months of such movement, with a frequency of six months, the planetary axis is located in such a way that both hemispheres are in the same conditions for heating. At this time (in March and September - the days of the equinox) the temperature regimes are approximately equal. Then, depending on the hemisphere, autumn and spring come.

earth axis

Our planet is a spinning ball. Its movement is carried out around a conditional axis and occurs according to the principle of a top. Leaning with the base in the plane in the untwisted state, it will maintain balance. When the speed of rotation weakens, the top falls.

The earth has no stop. The forces of attraction of the Sun, the Moon and other objects of the system and the Universe act on the planet. Nevertheless, it maintains a constant position in space. The speed of its rotation, obtained during the formation of the nucleus, is sufficient to maintain relative equilibrium.

The earth's axis passes through the planet's ball is not perpendicular. It is inclined at an angle of 66°33´. The rotation of the Earth on its axis and the Sun makes it possible to change the seasons of the year. The planet would "tumble" in space if it did not have a strict orientation. There would be no question of any constancy of environmental conditions and life processes on its surface.

Axial rotation of the Earth

The rotation of the Earth around the Sun (one revolution) occurs during the year. During the day it alternates between day and night. If you look at the Earth's North Pole from space, you can see how it rotates counterclockwise. It completes a full rotation in about 24 hours. This period is called a day.

The speed of rotation determines the speed of the change of day and night. In one hour, the planet rotates approximately 15 degrees. The speed of rotation at different points on its surface is different. This is due to the fact that it has a spherical shape. At the equator, the linear speed is 1669 km / h, or 464 m / s. Closer to the poles, this figure decreases. At the thirtieth latitude, the linear speed will already be 1445 km / h (400 m / s).

Due to axial rotation, the planet has a slightly compressed shape from the poles. Also, this movement "forces" moving objects (including air and water flows) to deviate from the original direction (Coriolis force). Another important consequence of this rotation is the ebbs and flows.

the change of night and day

A spherical object with the only light source at a certain moment is only half illuminated. In relation to our planet in one part of it at this moment there will be a day. The unlit part will be hidden from the Sun - there is night. Axial rotation makes it possible to change these periods.

In addition to the light regime, the conditions for heating the surface of the planet with the energy of the luminary change. This cycle is important. The speed of change of light and thermal regimes is carried out relatively quickly. In 24 hours, the surface does not have time to either overheat or cool below the optimum.

The rotation of the Earth around the Sun and its axis with a relatively constant speed is of decisive importance for the animal world. Without the constancy of the orbit, the planet would not have stayed in the zone of optimal heating. Without axial rotation, day and night would last for six months. Neither one nor the other would contribute to the origin and preservation of life.

Uneven rotation

Mankind has become accustomed to the fact that the change of day and night occurs constantly. This served as a kind of standard of time and a symbol of the uniformity of life processes. The period of rotation of the Earth around the Sun to a certain extent is influenced by the ellipse of the orbit and other planets of the system.

Another feature is the change in the length of the day. The axial rotation of the Earth is uneven. There are several main reasons. Seasonal fluctuations associated with the dynamics of the atmosphere and the distribution of precipitation are important. In addition, the tidal wave, directed against the motion of the planet, constantly slows it down. This figure is negligible (for 40 thousand years for 1 second). But over 1 billion years, under the influence of this, the length of the day increased by 7 hours (from 17 to 24).

The consequences of the Earth's rotation around the Sun and its axis are being studied. These studies are of great practical and scientific importance. They are used not only to accurately determine stellar coordinates, but also to identify patterns that can affect human life processes and natural phenomena in hydrometeorology and other fields.

The earth makes 11 different movements. Of these, they are of great geographical importance. diurnal movement e around the axis and annual circulation around the sun.

The following definitions are introduced: aphelion- the most distant point in the orbit from the Sun (152 million km), the Earth passes through it on July 5th. Perihelion- the nearest 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 slower the speed. Therefore, in the northern hemisphere, winter is shorter than summer. The earth rotates on its axis from west to east, making a complete revolution per day. The axis of rotation is constantly inclined to the plane of the orbit at an angle of 66.5°.

diurnal movement.

The movement of the earth around its axis is from west to east , a complete revolution is completed in 23 hours 56 minutes 4 seconds. This time is taken as day. At the same time, the Sun is rises in the east and moves to the west. The daily 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 deviation of horizontally moving bodies in the Northern Hemisphere to the right, in the Southern Hemisphere - to the left, this affects the direction of movement of air masses, sea currents, etc .;
• occurrence of ebbs and flows.

Earth's annual revolution

Earth's annual revolution is the movement of the earth in an elliptical orbit around the sun. The earth's axis is inclined to the plane of the orbit at an angle of 66.5°. When revolving around the Sun, the direction of the earth's axis does not change - it remains parallel to itself.

geographical consequence Earth's annual rotation is change of seasons , which is also due to the constant tilt of the earth's axis. If the earth's axis did not have an inclination, then during the year on Earth the day would be equal to the night, the equatorial regions would receive the most heat, and it would always be cold at the poles. The seasonal rhythm of nature (the change of seasons) is manifested in a change in various meteorological elements - air temperature, its humidity, as well as in a change in the regime of water bodies, the life of plants and animals, etc.

The Earth's orbit has several important points corresponding to the days equinoxes and solstices.

June, 22 The summer solstice is the longest day of the year in the Northern Hemisphere and the shortest day in the Southern Hemisphere. On the Arctic Circle and inside it on this day - polar day , on the Antarctic Circle and inside it - polar night .

December 22- the day of the winter solstice, in the northern hemisphere - the shortest, in the southern - the longest day of the year. Within the Arctic Circle - polar night , the Antarctic Circle - polar day .

March 21 and 23 September- the days of the spring and autumn equinoxes, since the rays of the Sun fall vertically on the equator, on the whole Earth (except for the poles) the day is equal to the night.