The Earth makes few different movements: together with the Galaxy towards the constellations Lyra and Hercules at a speed of 20 km/sec., rotational motion relative to the Center of the Galaxy with V = 250-280 km/sec. speed 0.5 km/sec. and others. This complex system of movements causes a number of phenomena on earth, formulating natural conditions. Consider only 2 movements that are important for the environment and humans.
daily rotation.
When observing the sun and planets from the Earth, it seems that the Earth is stationary, and the sun and planets revolve around it (the effect of the moving station). Just such a model (geocentric), the author of which is Ptolemy (2nd century BC) existed until the 16th century. However, as evidence accumulated, this model began to be questioned. The first person to publicly speak out against it was the Pole Nicolaus Copernicus. After his death, the ideas of Copernicus were developed by the Italian Giordano Bruno, who was burned at the stake, because. refused to cooperate with the Inquisition. His compatriot Galileo continued to develop the ideas of Copernicus and Bruno and, with the help of the telescope he invented, confirmed the correctness of his own.
Thus, already at the beginning of the 17th century. The rotation of the earth on its axis was proven. At present, this fact does not raise any doubts, and we have many proofs of axial rotation.
One of the most simple and convincing is the experiment with the Foucault pendulum. In 1851 the Frenchman L. Foucault, using a huge pendulum, showed that the plane of the pendulum is constantly shifting clockwise (when viewed from above). If the Earth did not rotate from west to east (counterclockwise), then there would be no such effect with the pendulum.
The second convincing evidence of the axial rotation of the Earth is the deviation of falling bodies to the east, i.e. if a load is dropped from a high tower, it will fall to the Earth, deviating from the vertical by several mm. or see depending on height.
The globe rotates around its own axis - as all planets rotate around their axes. And all almost revolve in the same direction as around the Sun. Those places where the axis of rotation of the planets intersects with their surface are called poles (at the Earth - geographic poles, South and North). A line that runs along the surface of the planet at an equal distance from both poles is called the equator.
Geographic poles do not stay in one place, but move along the surface of the planet. Fortunately for us, not very far and not very fast.
Observations at the stations of the International Earth Pole Motion Service (until 1961 it was called the International Latitude Service; and was created in 1899), as well as twenty years of measurements using geodetic satellites, indicate that the geographic poles are moving at a speed of 10 cm. in year.
What are the consequences associated with the daily rotation of the Earth?
First, it is the change of day and night. Moreover, due to the comparative gap between day and night, the atmosphere and the surface of the Earth do not have time to supercool and warm up. The change of day and night, in turn, causes the rhythm of many processes in nature (biorhythms).
Secondly, an important consequence of rotation is the deviation of horizontally moving bodies to the right in the northern hemisphere and to the left in the southern. Deflecting force or Coriolis force - is associated with a shift in time of the direction of the meridians and parallels. At the pole, where the parallels and meridians are almost parallel to each other, this force is zero, and at the equator, where they are at the greatest angle, the force is maximum.
The Coriolis effect is of great importance for objects moving in the meridional direction for a long time (river waters, air masses, etc.), this effect becomes noticeable: rivers wash away one of the banks more strongly than the other. And the winds blowing in one direction for a long time shift noticeably. The most important manifestation of such a shift is the twisting of winds in areas of high (anticyclones) and low (cyclones) atmospheric pressure.
Thirdly, an important consequence is the ebbs and flows. Rotating, the Earth periodically falls under the attraction of the Moon, in connection with which a tidal wave arises. During the new moon and full moon, the tides are maximum, during the 1/4 phase of the moon they are minimum.
The rotation of the earth has long been used to measure time. A complete rotation of the Earth around its axis occurs in different time intervals, depending on the reference point. Relative to the stars, a complete revolution occurs in 23 hours. 56min.4sec. (star days). And relative to the sun - for 24 hours. (solar day). However, these are average solar days, as clear solar days vary throughout the year.
In addition to local time (mean solar day), which depends on the position of the local meridian relative to the sun, there is a standard time system. In this regard, the entire globe is divided into 24 zones, with zero, which passes through the Greenwich meridian. Each zone differs in time from the next one by 1 hour. In the east, 1 hour more, and in the west, 1 hour less.
The earth revolves around the sun in an elliptical orbit speed 29.8 km / s, making a complete revolution in 365 days. 6 o'clock 9 min. 9.6 sec. This is sidereal or sidereal year - the time interval between two successive passages of the Earth through the same point in the orbit. At the end of the sidereal year, the observer will see the Sun near the same star where it was a year ago. However, the activity of people is not connected with sidereal time: it is subordinated to solar time. The time interval between two successive passages of the Sun through the vernal equinox is called the tropical year, the duration of which is 365 days. 5 o'clock 48 min. 46sec.
The length of the orbit is 940 million km. The Sun is located at one of the foci of the Earth's orbit, as a result of which the distance between the Earth and the Sun during the year varies from 152 ( aphelion – July 5) to 149 ( perihelion - January 3) million km.
The Earth's axis is inclined to the plane of the orbit at an angle 66 30 . In the process of movement, the axis moves forward and parallel to itself, so the Earth occupies 4 characteristic positions: equinoxes and solstices . On the days of the equinoxes, March 21 and September 23, the zenithal ray of the Sun falls on the equator, the border of light and shadow passes through the poles and divides each parallel into equal parts, so day is equal to night at all latitudes. At the same time, the northern and southern hemispheres receive heat and light equally.
On the day of the summer solstice, June 22, the Sun is at its zenith over the northern tropic, the border of light and shadow is tangent to the lines of the polar circles. Receives light and warmth most of the northern hemisphere, so it's summer here, and all of its arctic area is illuminated, so it's a polar day. The southern hemisphere receives a minimum of heat and light, so it is winter there, and its polar region is in the position of polar night.
On the day of the winter solstice, December 22, the Sun is at its zenith over the southern tropic and the illumination of the hemispheres changes in the opposite direction.
Thus, the change of seasons is due to the rotation of the Earth around the Sun with an inclined position of the axis. The seasonal rhythm of processes and phenomena in the geographic envelope is associated with the change of seasons.
Savtsova T.M. General geography, M., 2003, pp. 45-50
Milkov F.N. "General geography", M., 1990, pp. 59-62
Lyubushkina S.G. General Geography, M., 2004, pp. 19-22
LZ 7-8. Planetary factors of GO formation. Axial rotation of the Earth
1. Evidence for the Earth's axial rotation
2. Consequences of the axial rotation of the Earth
1. Evidence for the Earth's axial rotation
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.
When the Earth moves around the Sun, the imaginary axis of the Earth remains always inclined at an angle of 66.5 o to the plane of the Earth's orbit. These two factors - the tilt of the axis and the movement of the Earth around the Sun - lead to the change of seasons. The tilt of the axis causes a different angle of incidence of the sun's rays, and consequently, a different supply of solar radiation to the earth's surface and an unequal length of day and night. The seasonal rhythm of nature is connected with the change of seasons.
Let us consider the position of the Earth in the most characteristic periods. For example, the tilt of the axis on March 21 and September 23 (during the spring and autumn equinoxes) turns out to be neutral with respect to the Sun 1 . At the same time, both hemispheres of the Earth (both northern and southern) are equally illuminated by the Sun. At all latitudes in these periods, the duration of the day and night is 12 hours. On the days of the spring and autumn equinoxes, the sun's rays fall vertically at the equator, i.e. The sun is at its zenith at the equator at noon.
On June 22 (summer solstice), the Earth takes such a position that the northern end of its axis is tilted towards the Sun, while the northern hemisphere is illuminated to the maximum. The sun's rays fall vertically no longer on the equator, but on the northern tropic (the Tropic of Cancer), whose latitude is 23.5 o N. Thus, on June 22, the Sun at noon is at its zenith over the northern tropic. At 66.5 about north latitude (Arctic Circle) on June 22, a polar day is observed, i.e. The sun does not set below the horizon for exactly one day. Around the clock, not only the latitude of the Arctic Circle, but also the entire space to the north of it, up to the North Pole, is illuminated.
At 66.5 about south latitude (Southern Arctic Circle) and south of it to the South Pole on June 22, polar night. June 22 is the longest day of the year in the northern hemisphere, and the shortest day in the southern hemisphere.
December 22 (winter solstice) is the opposite. The sun's rays are already falling sheer on the southern tropic (the Tropic of Capricorn). At the latitude of the Antarctic Circle and to the south of it - the polar day, and at the latitude of the Arctic Circle and to the north of it - the polar night. The earth is positioned so that the southern hemisphere is more illuminated than the northern. December 22 is the shortest day of the year in the northern hemisphere and the longest day in the southern hemisphere.
On the globe, five belts of illumination can be distinguished, the boundaries of which are the tropics and the polar circles. The tropical zone (occupies 40% of the earth's surface) is characterized by the fact that at any point in it the Sun at noon happens twice a year at the zenith, in the tropics themselves - one; on the northern tropic on June 22, on the southern - on December 22. Throughout the year in the tropical zone, the difference between the length of the day and the length of the night is negligible, and twilight is short. There are practically no seasons.
Two temperate belts (occupy 52% of the earth's surface). There are tangible contrasts in the length of day and night depending on the season. Twilight is long. In summer, the Sun is high above the horizon (especially near the tropics), although it does not reach the zenith position; the summer day is very long (especially near the polar circles), but there is no polar day. Accordingly, in winter the Sun is low above the horizon, the winter day is very short. The change of four seasons is clearly expressed.
The two polar belts occupy 8% of the earth's surface. They are characterized by the following features: in summer - a polar day lasting from one day at the latitude of the Arctic Circle to six months at the pole, respectively, in winter - a polar night with a similar duration. The seasons of the year are weakly expressed: very cold long winters and short cold summers.
In addition to the fact that the Earth revolves around the Sun, it also rotates around its own axis (daily rotation). The direction of rotation is from west to east, as viewed from the North Star. The Earth makes one revolution around its axis in 23 hours 56 minutes. 4 sec. - 1 day). Each point on the earth's surface, except for the poles, describes a circle within a day of greater or lesser magnitude, if we assume that the axis is motionless. As a result of this, it seems to us that the celestial bodies move from east to west. An experimental proof of the rotation of the Earth around its axis is the experiment with the Foucault pendulum. There are several geographic consequences associated with the axial rotation of the Earth:
compression of the Earth from the poles;
the change of day and night, which is associated with the daily rhythm of nature;
emergence of the Coriolis force. With any movement in a rotating system, this force is directed perpendicular to the axis of rotation. Due to the Coriolis force, winds in temperate latitudes of both hemispheres take a predominantly westerly direction, and in tropical latitudes - east (trade winds). A similar manifestation of the Coriolis force is found in the direction of movement of ocean waters. The Coriolis force also explains the Baer-Babinet law, according to which the right banks of the rivers of the northern hemisphere are steeper than the left, and in the southern hemisphere the situation is the opposite.
The basic units of time are year and day. The length of a year is determined by the period of revolution of the Earth around the Sun, and the length of a day is determined by the period of time during which the Earth makes a complete rotation around its axis.
The path along which the Earth makes an annual movement is called its orbit. The orbit of the Earth, like the orbits of other planets in the solar system, has the shape of an ellipse. The earth's axis is inclined to the plane of the orbit at an angle 66°33'. The plane of the earth's equator with the plane of the orbit make an angle 23°27"(Fig. 1).
The period of complete revolution of the Earth around the Sun, i.e., the time interval between two successive passages of the center of the Earth through the vernal equinox, is called tropical year.
The point of the vernal equinox the point in the orbit at which the Earth is on March 21 is called, the autumn equinox occurs on September 23. At this time, at all latitudes of the Earth, excluding the regions of the earth's poles, day is equal to night.
The tropical year is 365 days 5 hours 48 minutes 46.1 seconds. For the convenience of using the calendar, the year is considered equal to 365 days 6 hours, or three years of 365 days, and every fourth 366 days (leap year).
For the basic unit of measurement of time taken sidereal day- the period between two successive upper culminations of a star (the vernal equinoxes). A sidereal day is 23 hours 56 minutes 4 seconds. During this period of time, the Earth rotates exactly 360 °.
In everyday life, it is impossible to use sidereal time, since all human activity is inextricably linked with the Sun, and not with the stars. In addition, sidereal days during the year begin at different times of the day and night, which is also inconvenient.
Rice. 1 Movement of the Earth around the Sun.
Time can be kept from the apparent motion of the Sun. The time interval between two successive upper culminations of the center of the Sun is called a true solar day. However, it is inconvenient to use them, since the duration of the true solar day during the year is not constant. The reasons for this are the uneven motion of the Sun along the ecliptic and the inclination of the ecliptic to the celestial equator at an angle 23°27'. Therefore, we agreed on the account of time; about the so-called mean sun. The time interval between two successive upper culminations of the average Sun is called the average solar day, but the beginning of the average solar day was considered the moment not of the upper (middle noon), but of the lower climax (midnight). The mean solar time, counted from the moment of the lower culmination, is called civil time. It differs from mean solar time by exactly 12 hours.
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Rice. 2 Map of time zones of Eurasia
The mean solar time, measured relative to the observer's meridian, is called local Tm.
Local time measured from the Greenwich meridian (zero meridian) is called Greenwich Tgr or world.
The use of local time in everyday life creates significant inconveniences, since when moving from one point to another, you need to continuously move the clock hands, consistent with the local time of each point. To avoid this, almost all countries use standard time Tp.
The essence of zone time lies in the fact that the entire globe is divided from west to east by meridians into 24 time zones, differing from each other in longitude by 15 °. All time zones are widest at the equator; to the north and south they gradually narrow and converge at the poles.
Each belt has its own number: zero, first, second, etc. up to the 23rd (Fig. 2). The zero belt was chosen with the calculation of the position of the Greenwich meridian in the middle of the belt. Belt numbers increase eastward; the difference in longitude between the average meridians of neighboring time zones is 15°. Consequently, the time difference between each zone is 1 hour. A single time is set inside the zone, corresponding to the local civil time of the middle meridian of this zone. Since the average meridian of each belt is 7.5 ° from the extreme meridians, then for the points located on the borders of the belt, standard time differs from their own local time by 0.5 hours.
When crossing the border of the belt, the clock hands are rearranged exactly one hour forward or backward, depending on which border is crossed: east or west. If the eastern border is crossed, the hands of the clock are moved forward 1 hour, and if the western border is crossed, then the hands are moved back 1 hour. In the zero zone, time is calculated according to Greenwich local time.
The boundaries of time zones pass exactly along the meridians only in deserts and oceans. In the rest of the world, the boundaries of time zones usually pass along the boundaries of administrative and state divisions, as a result, at some points located on the borders of such zones, local time may differ from the standard time of this zone by more than 30 minutes.
The boundaries of time zones are established by the relevant regulations of the government bodies of each state. Standard time on the territory of our country was introduced by a decree of the Council of People's Commissars of February 8, 1919, signed by V. I. Lenin. On the territory of the USSR, 11 time zones were established - from the second to the twelfth inclusive.
In addition, by decree of the Council of People's Commissars of the USSR of June 16, 1930, all clocks in our country were moved one hour ahead of standard time. This time is called maternity time Td.
Moscow time Tmsk call the time of the middle meridian of the second time zone plus the daylight hours.
For the transition from one time measurement system to another, the following relations are used:
Tm=Tp +l - N,
Tp=Tm- l + N,
where tm- local time of the point;
Tp- local time of the point;
l- longitude of the given point, expressed in units of time;
N- time zone number.
Note. On the territory of the USSR, all points have eastern longitude, and time zones are located east of the zero zone. Therefore, to obtain local time, you need to add longitude expressed in time to standard time and subtract the time zone number.
The conversion of Moscow time to Greenwich Mean Time is done by subtracting the number of the 2nd zone and one hour from Moscow standard time:
Tgr \u003d Tmsk - (2 + 1).
To switch from Greenwich time to standard time, you need to add the zone number and the daylight hours to Greenwich time:
Tp=Tgr + N+1.
Date line-(demarcation time line) is a conditionally drawn line that runs approximately along the 180 ° meridian along the water surface, skirting the islands and capes.
By international agreement, the new date begins on the western side of the demarcation line. On its eastern side, a new date occurs only after 24 hours .
Therefore, when crossing the date line from west to east from midnight following the transition of this line, the date repeats (the calendar shows the same date for two days). At. crossing this line from east to west at midnight after the transition, its date changes immediately by two units (one number falls out of the calendar). Therefore, aircraft crews, when crossing the date line, adhere to the following established procedure for changing the date in the logbook:
when crossing the date line in an easterly direction, after a day, the number (date) is repeated;
when crossing the date line in the western direction, one is added to the coming number.
In the Russian Federation, the date line is located on the eastern coast of the Chukotka Peninsula.
The earth is involved in several types of movement: around its own axis, together with other planets of the solar system around the sun, together with the solar system around the center of the galaxy, etc. However, the most important for the nature of the Earth are movement around its own axis and around the sun. The movement of the earth around its own axis is called axial rotation. It is carried out in the direction from west to east(counterclockwise as viewed from the North Pole). The period of axial rotation is approximately 24 hours (23 hours 56 minutes 4 seconds), i.e. earth days. Therefore, the axial movement is called daily. The axial motion of the Earth has at least four main consequences : the figure of the earth; the change of night and day; the emergence of the Coriolis force; occurrence of ebbs and flows. Due to the Earth's axial rotation, polar contraction, so its figure is an ellipsoid of revolution.Rotating around its axis, the Earth “directs” one hemisphere, then the other, towards the Sun. On the illuminated side day, on unlit - night. The duration of day and night at different latitudes is determined by the position of the Earth in orbit. In connection with the change of day and night, a daily rhythm is observed, which is most pronounced in wildlife objects.Earth's rotation "forces" moving bodies deviate from the direction of its original movement, and in Northern Hemisphere - to the right, and in the Southern - to the left. The deflecting action of the earth's rotation is called Coriolis forces. The most striking manifestations of this power are deviations in the direction of movement of air masses(the trade winds of both hemispheres acquire an eastern component), ocean currents, river flows. The attraction of the Moon and the Sun, together with the axial rotation of the Earth, cause the occurrence of tidal phenomena. A tidal wave circles the Earth twice a day. Ebb and flow are characteristic of all geospheres of the Earth, but they are most clearly expressed in the hydrosphere. No less important for the nature of the earth is its orbital motion around the sun. The shaving of the Earth has an elliptical shape, that is, at its different points, the distance between the Earth and the Sun is not the same. AT July Earth is further from the Sun (152 million km), and therefore its orbital motion slows down slightly. As a result, the Northern Hemisphere receives more heat than the Southern Hemisphere, and summers are longer here. AT January the distance between the Earth and the Sun is minimal and equals 147 million km. The orbital period is 365 full days and 6 hours. Everyone fourth year counts leap year, that is, it contains 366 days, insofar as for 4 years, extra days accumulate. It is generally accepted that the main consequence of orbital motion is the change of seasons. However, this occurs not only as a result of the annual motion of the Earth, but also due to the inclination of the earth's axis to the plane of the ecliptic, and also due to the constancy of the value of this angle, which is 66.5°. The Earth's orbit has several key points that correspond to the days of the equinoxes and solstices. June, 22 – summer solstice day. On this day, the Earth is turned towards the Sun by the Northern Hemisphere, so it is summer in this hemisphere. The sun's rays are incident at right angles on a parallel 23.5°N- northern tropic. On the Arctic Circle and within it - polar day, on the Antarctic Circle and south of it - polar night. December 22, in winter solstice, the Earth in relation to the Sun occupies, as it were, the opposite position. During the equinoxes, both hemispheres are equally illuminated by the sun. The sun's rays fall at right angles to the equator. Throughout the Earth, except for the poles, the day is equal to the night, and its duration is 12 hours. At the poles there is a change of polar day and night.
