The earth rotates around an inclined axis from west to east. Half the globe illuminated by the sun, there is day at this time, the second half is in the shade, there is night. Due to the rotation of the Earth, there is a change of day and night. The Earth makes one revolution around its axis in 24 hours - a day.
Due to rotation, moving streams (rivers, winds) in the northern hemisphere are deflected to the right, and in the southern hemisphere - to the left.
Rotation of the Earth around the Sun
The Earth revolves around the sun in a circular orbit, a complete revolution takes 1 year. The Earth's axis is not vertical, it is inclined at an angle of 66.5° to the orbit, this angle remains constant during the entire rotation. The main consequence of this rotation is the change of seasons.
Consider the rotation of the Earth around the Sun.
- December 22- day winter solstice. Closest to the sun (the sun is at its zenith) at this moment is the southern tropic - therefore, summer is in the southern hemisphere, winter is in the northern hemisphere. The nights in the southern hemisphere are short, at the southern polar circle on December 22 the day lasts 24 hours, the night does not come. In the Northern Hemisphere, the opposite is true; in the Arctic Circle, the night lasts 24 hours.
- 22nd of June- the day of the summer solstice. The northern tropic is closest to the sun, in the northern hemisphere it is summer, in the southern hemisphere it is winter. In the southern polar circle, night lasts 24 hours, and in the northern polar circle, night does not come at all.
- March 21, September 23- the days of the spring and autumn equinoxes. The equator is closest to the sun, the day is equal to the night in both hemispheres.
For the nature of the earth's surface, the axial rotation of the earth is of great importance.
1.
It will create the basic unit of time - a day, divided into two main parts - illuminated and unlit. With this unit of time, in the process of evolution of the organic world, the physiological activity of animals and plants turned out to be coordinated. The change of tension (work) and relaxation (rest) is an internal need of organisms. Its rhythms could be different, but in the process of evolution there was a selection of such organisms, the internal biological "clock" of which "works" daily.
Master Synchronizer biological rhythms there is an alternation of light and dark. It is associated with the rhythm of photosynthesis, cell division and growth, respiration, the glow of algae and much more.
Since the length of the day varies with the seasons, the daily rhythm in animals and plants varies between 23-26, and in some 22-28 hours.
The most important feature of the thermal regime (and not the amount of heat) of the earth's surface depends on the day - the change of daytime heating and nighttime cooling. It is not only change that is important; but also their duration.
The daily rhythm is also manifested in inanimate nature: in the heating and cooling of rocks and weathering, the temperature regime of reservoirs, air temperature and winds, ground precipitation.
2.
The second essential meaning of the rotation of geographic space is its division into right and left. This causes the paths of moving bodies to deviate to the right in the northern hemisphere and to the left in the southern.
In 1826, the historian P. A. Slovtsov pointed to the erosion of the right banks of Siberian rivers. In 1857, the Russian academician K. M. Baer expressed general position that all the rivers of the northern hemisphere wash away the right banks. In 1835, the French mathematician G. Coriolis formulated the theory of the relative motion of bodies in a rotating frame of reference. Rotating geographic space is such a mobile system. The deviation of the paths of movement of bodies to the right or to the left is called the Coriolis force or Coriolis acceleration.
The essence of the phenomenon is as follows. The direction of movement of bodies, of course, is rectilinear relative to the axis of the World. But on Earth, it occurs on a rotating sphere, under a moving body the horizon plane turns to the left in the northern hemisphere and to the right in the southern. Since the observer is on a solid surface of a rotating sphere, it seems to him that the moving body is deviated to the right, while in fact the horizon plane is moving to the left.
The Coriolis force can be seen most clearly in the swing of a Foucault pendulum. A load suspended on a free thread oscillates in one plane with respect to the axis of the World. The disk under the pendulum rotates with the Earth. Therefore, each swing of the pendulum with respect to the disk takes place in a new direction. In Leningrad (φ=60°) the disk under the pendulum rotates by 15°sin 60°-13° within an hour, where 15° is the angle of rotation of the Earth during the hour.
The deviation of the path of motion from the original direction of any mass in physical essence is the same as the deviation of Foucault's pendulum.
Conservation by the masses, due to inertia, rectilinear motion and the simultaneous rotation of the earth's surface cause a visible deviation of the directions of movement to the right in the northern and to the left in the southern hemispheres, regardless of whether the mass moves along the meridian or along the parallel.
Thus, the deflecting force of the Earth's rotation is directly proportional to the mass of the moving body, the speed of movement and the sine of latitude. At the equator, it is 0 and increases with latitude.
All moving masses are subject to the action of the Coriolis force: water in ocean and sea currents, in rivers, air masses in the process of atmospheric circulation, matter in the Earth's core; Coriolis force is also taken into account in ballistics.
3. The rotation of the Earth (together with the spherical shape) in the field of solar radiation (light and heat) determines the west-east extension of the zones of nature.
4. We have already seen the geodesic (for the figure of the planet) and geophysical (for the redistribution of masses in its body) consequences of the uneven rotational regime of the Earth.
5. Due to the rotation of the Earth, ascending and descending air currents, disordered in different places, acquire predominant helicity: in the northern hemisphere, a left screw is formed, in the southern hemisphere, a right one. Air masses, ocean waters, and also, probably, the substance of the core obey this pattern.
Movement around its own axis. The earth rotates from west to east, counterclockwise, while the angular velocity of rotation, i.e. the angle by which any point on the surface of the Earth rotates is the same and is 15 degrees per hour. Linear speed depends on latitude
terrain: at the equator it is maximum and is 464 m / s, at the poles the speed drops to zero. Our planet makes a complete rotation around its axis in 23 hours 56 minutes 4 seconds. (day). The earth's axis is an imaginary straight line passing through the poles, around which the earth rotates. The equator is located perpendicular to the axis - this is a large circle formed by the intersection of the Earth, perpendicular to the axis of rotation at a distance equal to both poles. If you mentally cross a number of planes parallel to the equator, lines called parallels will appear on the earth's surface. They have a west-east direction. The length of the parallels from the equator to the poles decreases, and the speed of rotation of the points decreases accordingly. If you cross the Earth with planes passing through the axis of rotation, then lines appear on the surface, which are called meridians. They have a north-south direction, the linear speed of rotation of points on the meridians is different and decreases from the equator to the poles.
Consequences of the Earth's motion around its axis:
1. During the rotation of the Earth, a centrifugal force arises, which plays an important role in shaping the figure of the planet and thereby reduces the force of attraction.
2. There is a change of day and night.
3 There is a deviation of bodies from the direction of their movement, this process was called the Coriolis force. All bodies, by inertia, tend to maintain the direction of their movement. If the movement occurs relative to the moving surface, this body deviates slightly to the side. All bodies moving in the northern hemisphere deviate to the right, in the southern hemisphere - to the left. Given power manifests itself in many processes: it changes the movement of air masses, sea currents. For this reason, the right banks in the northern hemisphere and the left banks in the southern hemisphere are washed away.
4. The phenomena of daily rhythm and biorhythms are associated with axial movement. The daily rhythm is associated with light and temperature conditions. Biorhythms are an important process in the development and existence of life. Without them, photosynthesis, the vital activity of diurnal and nocturnal animals and plants and, of course, the life of the person himself (owl people, lark people) are impossible.
5) Proof of the rotation of the earth.
In the middle of the 19th century, Jean Bernard Leon Foucault was able to conduct an experiment that demonstrates the rotation of the Earth quite clearly. This experience was carried out repeatedly, and the experimenter himself presented it publicly in 1851 in the building of the Pantheon in Paris.
The building of the Paris Pantheon in the center is crowned with a huge dome, to which a steel wire 67 m long was attached. A massive metal ball was suspended from this wire. According to various sources, the mass of the ball ranged from 25 to 28 kg. The wire was attached to the dome in such a way that the resulting pendulum could swing in any plane.
The pendulum oscillated over a round pedestal with a diameter of 6 m, along the edge of which a roller of sand was poured. With each swing of the pendulum, a sharp rod, mounted on the ball from below, left a mark on the roller, sweeping sand from the fence.
After each period, a new mark made by the tip of the rod in the sand turned out to be about 3 mm from the previous one. During the first hour of observations, the plane of the pendulum's swings rotated by an angle of about 11° clockwise. The plane of the pendulum made a complete revolution in about 32 hours.
The experiment was based on the experimental fact already known at that time: the plane of swing of the pendulum on the thread is preserved regardless of the rotation of the base to which the pendulum is suspended. The pendulum tends to preserve the parameters of motion in an inertial frame of reference, the plane of which is stationary relative to the stars. If the Foucault pendulum is placed at the pole, then the plane of the pendulum will remain unchanged during the rotation of the Earth, and observers rotating with the planet should see how the plane of the pendulum swings without any forces acting on it. Thus, the period of rotation of the pendulum at the pole is equal to the period of rotation of the Earth around its axis - 24 hours. At other latitudes, the period will be somewhat longer, since the pendulum is affected by inertial forces arising in rotating systems - the Coriolis forces. At the equator, the plane of the pendulum will not rotate - the period is equal to infinity.
6) Coriolis acceleration and its significance for processes in geographical envelope
.
There is a deviation of the bodies from the direction of their movement, this process was called the Coriolis force. All bodies, by inertia, tend to maintain the direction of their movement. If the movement occurs relative to the moving surface, this body deviates slightly to the side. All bodies moving in the northern hemisphere deviate to the right, in the southern hemisphere - to the left. This force is manifested in many processes: it changes the movement of air masses, sea currents. For this reason, the right banks are washed away in the northern hemisphere and the left banks in the southern hemisphere.
It is named after the French scientist Gustave Gaspard Coriolis, who described it in 1833.
7) The revolution of the Earth around the Sun and its consequences.
The path of the Earth around the Sun is called an orbit. The Earth's orbit is an ellipse close to a circle. Its length is more than 930 million km. The Earth makes a complete revolution in 365 days 6 hours and 9 minutes. This interval is called a sidereal year.
The earth rotates around its axis from west to east, making a complete revolution in 23 hours 56 minutes. 4 s. (star days). Angular velocity all points of the Earth is the same: 15 h (360 h.). Line speed their depends on the distance that the points must travel during the period of daily rotation. The maximum linear speed at the equator is 464 m/s, at the poles -0, at other latitudes it is calculated by the formula:
V cos m/s, where is the latitude of the place
One of the proofs of the daily rotation of the Earth is Foucault's experiment, which makes it possible to observe the rotation of the Earth and determine the angular velocity
W sin ( - location latitude)
The experimentally observed deviation of falling bodies to the east also indicates the rotation of the Earth around its axis.
The most important geographical consequences are the change of day and night, the deflecting force of the Earth's rotation (the Coriolis force) and the possibility of constructing a system of geographical coordinates. The change of night and day due to the rotation of the Earth in the parallel rays of the Sun, while half of the globe is always illuminated (day), the other is not illuminated (night). The change of day and night determines the daily rhythm of many processes and phenomena on Earth.
Thanks to Coriolis force all moving bodies (air, water, rockets, shells, etc.) deviate to the right in the northern hemisphere, and to the left in the southern hemisphere. Therefore, the right banks of rivers, the slopes of river valleys in the northern hemisphere are predominantly steep and precipitous. The action of the Coriolis force affects the direction of ocean currents (Gulf Stream, Kuroshio) and winds (western winds of temperate latitudes, trade winds).
On the surface of the Earth there are two remarkable points that are not involved in the rotation of the planet - the northern and south poles, relying on which it turned out to be possible to build a harmonious unified geographic coordinate system : network of meridians and parallels.
Due to the uneven motion of the Earth in orbit, a solar day cannot be used to measure the exact time. In practice, they use mean solar time . It is determined by the average Sun - an imaginary point that evenly passes along the celestial equator on its way in a year. The average solar day is equal to 24 average solar hours, which are divided into minutes and seconds. The beginning of the mean solar day is taken as the moment of the lower culmination of the mean Sun, i.e. midnight.
Times of the day - morning, afternoon, night, evening on different meridians begin at different times, but on the same meridian - at the same time.
A new day begins at 180 longitude, which is called date line . Each meridian has its own local time , and the further east it is located, the earlier the day begins on it. On meridians separated by 15, local time differs by 1 hour, and between neighboring meridians separated by 1 - by 4 minutes.
The coordinated activity of people requires a coordinated account of time, and as early as the 19th century, standard time . The earth's surface is divided into 24 time zones, each of which includes 15 longitude. In each time zone, the account is kept according to the local time of its middle meridian, which is also called zone time. In 1930, by a decree of the government of the USSR, in order to more rational use daylight hours, the hands of the clock were moved forward 1 hour ( maternity time ). During the summer months in many countries introduced summer time when the clock hands move forward 1 hour.
For astronomical work, it is advisable to use world (worldwide) time (Greenwich meridian).
Earth's attraction to other bodies solar system causes elastic deformations in the entire body of the planet (in the atmosphere, hydrosphere, lithosphere). The greatest influence is exerted by the Moon (2.17 times more than the Sun) and the Sun. If the tide-forming forces caused by the Moon and the Sun add up, which happens at the time of syzygy (full moon, new moon), then the height of the tides is greatest: in open ocean up to 77 cm, height increases near the coast. The maximum height of the tide in the Bay of Fundy is up to 18 m. At the moment of quadrature (the first and last quarter of the Moon), the height of the tides is low, because in this case, the force caused by the Sun is subtracted from the tide-forming force created by the Moon.
Earth tides generate tidal friction. Due to the high speed of the Earth's rotation, the tidal protrusions are displaced by the relative straight line connecting the centers of the Earth and the Moon, while the protrusion closest to the Moon (excess mass) slows down the speed of the Earth's rotation, and the far one accelerates it. Since the braking effect is stronger, the overall speed of the Earth's rotation slows down. A day in the pregeological stage of the Earth (4.5 billion years ago) was equal to 2 hours, 500 million years ago - 20 hours. The slow is 0.001 sec. for 100 years.
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 highest value for all living things, the rotation of the Earth around the Sun and its own axis plays. 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, there the temperature environment higher. 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 North Pole Earth 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. Rotation speed in different points 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
spherical object the only source light 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 have great practical and scientific significance. They are used not only for the accuracy of determining stellar coordinates, but also to identify patterns that can affect the processes of human life and natural phenomena in hydrometeorology and other fields.
