Schematic representation of the tilt of the earth's axis of rotation. Credit & Copyright: UniverseTodayRu
In ancient times, in various cultures, our planet took a variety of forms - from a cube to the more popular flat disk surrounded by the sea. But thanks to the development of astronomy, we have come to understand that in fact the Earth has a spherical shape (geoid), moreover, it is one of the many planets in our star system that revolves around the Sun.
Over the past few centuries, as a result of the development of science, the evolution of scientific instruments and more complex observations, astronomers have been able to determine the true shape of the Earth's orbit with high accuracy. In addition to knowing the exact distance to the Sun, we also found out that our planet revolves around it with a certain tilt.
The inclination of the axis of rotation is the angle by which the axis of rotation of the planet is deviated from the perpendicular drawn to the plane of its orbit. This kind of slope celestial body affects how much sunlight a certain point on its surface receives during the year. The tilt of the earth's axis of rotation is approximately 23.44° (or 23.439281° to be exact).
The tilt of the earth's axis is the main factor responsible for the seasonal changes that occur on the earth during the year. When the north pole is pointing towards the sun, it is summer in the northern hemisphere and winter in the southern hemisphere. When, after six months, the south pole turns towards the Sun, the opposite situation is observed.
In addition to temperature changes, the changing seasons also lead to changes in the daily cycle. So in summer, the length of the day is longer than the night, and the Sun rises higher in the sky. In winter, the days become shorter and the Sun is lower.
A more interesting situation is observed beyond the Arctic Circle: there, first, for almost six months, the Sun does not rise above the horizon (a phenomenon known as “polar night”), and then also does not set below the horizon for almost six months (“polar day”).
This illustration shows a view of the Earth from space. Credit & Copyright: NASA. Four seasons can be tied to four dates: solstices and equinoxes. In the northern hemisphere, the winter solstice occurs on December 21 or 22, the summer solstice on June 20 or 21, the spring equinox on March 20, and the autumn equinox on September 22 or 23. In the southern hemisphere, the situation is reversed: the date of the summer solstice changes with the date of the winter, and the date of the vernal equinox with the date of the autumn.
The tilt angle of the Earth is relatively stable over a long period of time. However, the earth's axis is constantly swinging. This phenomenon, known as precession, causes the seasons to “reverse” periodically (about every 25,800 years). When this happens, summer in the northern hemisphere will begin in December and winter in June.
Thus, the rotation of the Earth around its axis is not as easy as you might think. During scientific revolution for many it was a real revelation to know that the Earth is not a fixed point in the Universe. But even then, astronomers like Copernicus and Galileo believed that the Earth's orbit was a perfect circle, and they couldn't even imagine what it really looked like. And only after a long time did we realize that the tilt of our planet's axis leads to serious changes over time - both in the short and long term.
Team is any organizational group of people.
In pedagogical literature, a team is called an association of pupils who differ in a number of features:
· General social meaningful goal.
· Common compatible activities to achieve the goal.
· The general organization of this activity, the relation of responsible dependence.
· Commonly elected governing body.
· Favorable psychological climate.
Children's team how the system is:
1. A limited part of a more complex association, an educational team, including, in addition to children, a team of teachers.
2. Relatively autonomous system which is characterized by the processes of self-organization, self-government.
3. Coordinated unity of two structures:
Official (under the influence of adults)
Informal (in the process of communication)
4. The subject of activity for the implementation of common public significant goals.
5. The subject of education in relation to the personality of each of its members.
Functions of the children's team:
1. Educational.
2. Organizational.
3. Regulatory.
4. Stimulating.
The principles of forming a children's team in a team:
1. Organization of the detachment.
2. Organization of a team of different ages.
The children's team can be of the same age or of different ages. Boys and girls are developmentally different.
Z madәniyatenen үzenchәleklәren saklarga, head halyklarnyң madәniyaten һәm traditionalaryn khөrmәt itәrә.
Geographic Consequences of the Tilt of the Earth's Axis to the Orbital Plane
Geographic consequences of the annual movement of the Earth:
1. The earth's axis is inclined with respect to the plane of the orbit and forms an angle with it equal to 66 0 33 / . In the process of movement, the axis moves forward, so 4 characteristic points appear on the orbit:
March 21 and September 23- the days of the equinoxes - the tilt of the earth's axis is neutral with respect to the Sun, and the parts of the planet facing it are evenly illuminated from pole to pole. At all latitudes in these periods, the duration of the day and night is 12 hours.
June 21 and December 22- the days of the summer and winter solstices - the plane of the equator is inclined with respect to the sun's beam at an angle of 23 0 27 / , the Sun at this moment is at its zenith over one of the tropics.
2. The inclination of the earth's axis to the plane of the orbit is associated with the presence of such characteristic parallels as the tropics and the polar circles. The Arctic Circle is a parallel whose latitude is equal to the angle of inclination of the earth's axis to the plane of the orbit (66 0 33 /). Tropic - a parallel, the latitude of which complements the angle of inclination of the earth's axis to a straight line (23 0 27 /). The polar circles are the boundaries of the polar day and polar night. The tropics are the limits of the zenithal position of the sun at noon. In the tropics, the sun is at its zenith once, in the space between them twice a year.
3. Change of seasons (winter, spring, summer, autumn - the northern hemisphere (NH); summer, autumn, winter and spring - the southern hemisphere (SH). Characteristically uneven distribution of the year between seasons (spring contains 92.8 days, summer - 93.6, autumn - 89.8, winter - 89.0), which is explained by the division of the elliptical orbit of the Earth by the lines of solstices and equinoxes into unequal parts, which require different times to pass.
4. The formation of illumination belts, which are distinguished by the height of the Sun above the horizon and the duration of illumination. AT hot belt, located between the tropics, the Sun is at its zenith twice a year at noon. On the lines of the tropics, the Sun is at its zenith only once a year: on the Northern Tropic (Tropic of Cancer) the Sun is at its zenith at noon - June 22, on the Southern Tropic (Tropic of Capricorn) - on December 22.
Between the tropics and the polar circles stand out two temperate zones. In them, the Sun never stands at its zenith, the length of the day and the height of the Sun above the horizon vary greatly during the year.
Between the polar circles and the poles are two cold zones there are polar days and nights. Consequently, there are days in the year when the Sun does not appear above the horizon at all or does not fall below the horizon.
5. The change of seasons determines the annual rhythm in civil defense. In the hot zone, the annual rhythm depends mainly on changes in moisture, in the temperate zone, on temperature, and in the cold zone, on lighting conditions.
24. Daily motion of the Earth and its geographical consequences. The concept of "Starry Day" and "Solar Day"
Daily rotation of the Earth around its axis and its consequences. The earth rotates counter-clockwise from west to east, making a complete revolution in a day. The axis of rotation is deflected by 23 0 27 / from the perpendicular to the plane of the ecliptic. The average angular velocity of rotation, i.e. the angle by which the point is displaced earth's surface, for all latitudes is the same and is 15 0 for 1 hour. Line speed, i.e. the path traveled by a point per unit time depends on the latitude of the place. The geographic poles do not rotate, where the speed is zero. At the equator, each point travels the longest path and has the highest speed - 455 m / s. The speed on one meridian is different, on the same parallel it is the same.
The geographical consequences of the daily rotation of the Earth are:
1. Change of day and night, i.e. change during the day the position of the Sun relative to the plane of the horizon of a given point (axial rotation gives the basic unit of time - a day). The circadian rhythm is associated with this change. solar radiation, the intensity of which depends on the angle of the earth's axis, the rhythms of heating and cooling of local air circulation, and the vital activity of living organisms.
2. Different at the same moment the local time on different meridians (difference of 4 minutes for each degree of longitude).
3. Existence Coriolis forces(deflecting effect of the Earth's rotation). The Coriolis force is always perpendicular to the motion, directed to the right in the northern hemisphere and to the left in the southern. Its value depends on the speed of movement and the mass of the moving body, as well as on the latitude of the place: F = 2mυwsinφ,
where m is the body weight; υ is the linear velocity of the body; w is the angular velocity of the Earth's rotation (important only in the secular aspect, for short periods of time the angular velocity is assumed to be constant); φ is the latitude of the place.
At the equator, the Coriolis force is zero, its magnitude increases towards the poles. The Coriolis force contributes to the formation of atmospheric vortices, affects the deviation of sea currents. Thanks to it, the right banks of the rivers are washed away in the SP and the left banks in the SP.
4. 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.
5. Compression of the earth's spheroid, which is explained by the simultaneous action of two forces on any point of the planet: gravity (directed towards the center) and centrifugal (perpendicular to the axis of rotation), giving gravity. Gravity is the vector difference between gravity and centrifugal force. The centrifugal force increases from zero at the poles to a maximum at the equator. In accordance with the decrease in centrifugal force from the equator to the pole, the force of gravity increases in the same direction and reaches a maximum at the pole (equal to the force of gravity).
The deformation of the Earth's figure, due to differences in gravity, further emphasizes the increase in centrifugal force (decrease in gravity) towards the equator and, thus, further contributes to the oblateness of the Earth from the poles.
6. Axis of rotation, poles and equator are the basis geographical system coordinates. The equator serves as a plane of symmetry, relative to which the lighting belts are placed, the amount of solar radiation and other important parameters change. The direction of the Coriolis force depends on the hemisphere (Northern and Southern), and its magnitude depends on the latitude, the poles do not participate in the daily rotation.
7. Deformation of the figure of the Earth - oblateness at the poles (polar compression), associated with an increase in centrifugal force from the poles to the equator.
The rotation of the Earth around its axis serves as the basis for determining time using astronomical observations. The solar day used in Everyday life, are measured by the duration of one revolution of the Earth in relation to the Sun. Sidereal days are determined by the duration of one revolution of the Earth in relation to the stars.
A sidereal day is equal to 23 hours. 56 min. 4s. This is the time it takes for a star to cross the celestial meridian twice in succession. A solar day is equal to 24 hours - this is the time interval between two successive passages of the Sun through the celestial meridian (at noon).
A solar day is about 4 minutes longer than a sidereal day. due to the fact that the Earth simultaneously rotates on its axis and revolves around the Sun. Therefore, for the new appearance of the Sun on the celestial meridian, the Earth needs to turn around its axis a little more than once.
The earth's axis of our planet in the northern vector is directed to the point where the star of the second magnitude, called the Polaris, is located in the tail
This star during the day outlines on celestial sphere a small circle with a radius of about 50 minutes of arc.
In ancient times, they knew about the tilt of the earth's axis
A very long time ago, in the II century BC. e., the astronomer Hipparchus discovered that this point is mobile in the starry sky and slowly moves towards the movement of the Sun.
He calculated the rate of this movement at 1° per century. This discovery was called This move ahead, or the prelude to the equinox. The exact value of this movement, the constant precession, is 50 seconds per year. Based on this, a complete cycle along the ecliptic will be approximately 26,000 years.
Accuracy is important for science
Let's return to the question of the pole. Determining its exact position among the stars is one of the most important tasks of astrometry, which deals with measuring arcs and angles on the celestial sphere in order to determine the planets, proper movements and distances to the stars, as well as solving problems of practical astronomy that are important for geography, geodesy and navigation .
You can find the position of the pole of the world using photography. Imagine a long-focus photographic camera, implemented in the form of an astrograph, aimed motionlessly at a region of the sky near the pole. In such a photograph, each star will describe a more or less long arc of a circle with a single common center, which will be the pole of the world - the point where the rotation of the earth's axis is directed.
A little about the angle of the Earth's axis
The plane of the celestial equator, being perpendicular to the earth's axis, also changes its position, which causes the movement of the points of intersection of the equator with the ecliptic. In turn, the attraction of the equatorial displacement by the Moon tends to rotate the Earth in such a way that its equatorial plane intersects the Moon. But in this case, these forces act not on but on the masses that form the equatorial swelling of its ellipsoidal figure.
Imagine a ball inscribed in earth ellipsoid, which it touches at the poles. Such a ball is attracted by the Moon and the Sun by forces directed towards its center. For this reason, the earth's axis remains unchanged. This attraction, acting on the equatorial bulge, tends to rotate the Earth in such a way that the equator and the object attracting it coincide, thus creating an overturning moment.
The Sun moves away from the equator twice during the year up to ± 23.5 °, and the removal of the Moon from the equator during the month reaches almost ± 28.5 °.
Children's toy spinning top reveals a little secret
If the Earth did not rotate, then it would tend to tilt, as if nodding, so that the equator would follow the Sun and Moon all the time.
True, due to the huge mass and inertia of the Earth, such fluctuations would be very insignificant, since the Earth would not have time to react to such a rapid change in direction. We are well acquainted with this phenomenon on the example of a child's spinning top. tends to overturn the top, but the centripetal force protects it from falling. As a result, the axis moves, describing a conical shape. And the faster the movement, the narrower the figure. The earth's axis behaves in the same way. This is a certain guarantor of its stable position in space.
The angle of the Earth's axis affects the climate
The Earth moves around the Sun in an orbit that is almost like a circle. Observation of the speed of stars located near the ecliptic represents that at any moment we are approaching some stars and moving away from the opposite ones in the sky at a speed of 29.5 kilometers per hour. The change of the seasons is the result of that. There is an inclination of the earth's axis to the plane of the orbit and is about 66.5 degrees.
Due to the small elliptical orbit, the planet is somewhat closer to the Sun in January than in July, but the difference in distance is not significant. Therefore, the effect on the receipt of heat from our star is hardly noticeable.
Scientists believe that the earth's axis is an unstable parameter of our planet. Studies show that the angle of inclination of the earth's axis with respect to the plane of its orbit in the past was different and changed periodically. According to the legends that have come down to us about the death of Phaethon, in the descriptions of Plato there is a mention of an axis shift at this terrible time by 28 °. This catastrophe took place over ten thousand years ago.
Let's fantasize a little and change the angle of the Earth
The current angle of the earth's axis with respect to the plane of the orbit is 66.5 ° and provides for a not so sharp fluctuation in winter-summer temperatures. For example, if this angle were about 45°, what would happen at the latitude of Moscow (55.5°)? In May, under such conditions, the sun will reach the zenith (90°) and shift to 100° (55.5°+45°=100.5°).
With such an intense movement of the Sun, the spring period would pass much faster, and in May it would reach the peak of temperatures, as at the equator at maximum solstice. Then it would weaken slightly, as the sun, passing the zenith, would go a little further. Then it came back, passing the zenith again. For two months, in July and May, unbearable heat would be observed, about 45-50 degrees Celsius.
Now consider what would happen to winter, for example, in Moscow? After passing the second zenith, our luminary would have dropped to 10 degrees (55.5°-45°=10.5°) above the horizon in December. That is, with the approach of December, the sun would come out for a shorter period than now, rising low above the horizon. During this period, the sun would shine for 1-2 hours a day. Under such conditions, nighttime temperatures will drop below -50 degrees Celsius.
Every version of evolution has the right to life
As we can see, for the climate on the planet it is important at what angle the earth's axis. This is a fundamental phenomenon in the mildness of the climate and living conditions. Although, perhaps, under different conditions on the planet, evolution would have gone in a slightly different way, creating new types of animals. And life would continue to exist in its other diversity, and, perhaps, there would be a place for a “different” person in it.
earth axis
If you could look at the Earth from the side, you would think that the Earth has very bad posture. The Earth flies around the Sun, leaning somewhat to the side (like a sailboat in a strong wind).
The angle of the earth's axis
The angle of the earth's axis is 23.5 degrees from the vertical line. This happened during the deadly races that formed our solar system 4.6 billion years ago.
The Sun, Earth and the other eight planets in our planetary system formed from a rotating cloud of interstellar gas and dust. Scientists believe that the Earth grew to the size of a planet, absorbing particles that collided with it. Millions of years passed, worlds were formed and destroyed, planets were formed from their parts in modern form. The natural satellite of the Earth may have been formed during the collision of the red-hot Earth with a large cosmic body.
Why is the Earth's axis tilted?
According to Clark Chapman, an astronomer at the Planetary Science Institute in Tucson, Arizona, it took a gigantic explosion to give the Earth its current orbit. Thanks to the explosion, life on our home planet has become very interesting. The results of this blow still turn the leaves yellow in autumn, roast the Mediterranean coast in summer, allow children to frolic in rivers, and in winter cause heavy snowfalls to the delight of children and to the grief of city authorities. This last decisive explosion created the seasons on Earth - the four seasons.
What causes Earth's climate change?
Astronomer Milyutin Milankovich (1879-1958) studied the change in the Earth's orbit around the Sun and the tilt of our planet's axis. He suggested that cyclical changes between them are the cause of long-term climate change.
Climate change is a complex process, influenced by many factors. The main one is the relationship between the Earth and the Sun.
Milanković studied three factors:
Change in the tilt of the earth's axis;
Deviations in the shape of the Earth's orbit around the Sun;
The precession of the change in the position of the inclination of the axis with respect to the orbit..
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Deviation of the earth's axis. |
Change in the Earth's orbit. |
 Earth Earth without seasons, 0° axis tilt. |
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 End of June: summer in the Northern Hemisphere, winter in the Southern. |
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 Late December: summer in the Northern Hemisphere, winter in the Southern. |
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Tilt of the earth's axis
If there were no axial tilt, then we would have no seasons, and day and night would be the same throughout the year. The amount of solar energy reaching a certain point on Earth would be constant. Now the axis of the planet is at an angle of 23.5 °. In the summer (since June) in the Northern Hemisphere, it turns out that the northern latitudes get more light than the South. The days are getting longer and the position of the sun is higher. At the same time, it is winter in the Southern Hemisphere. The days are shorter and the sun is lower.
FROM six months later, the Earth moves in its orbit to the opposite side of the Sun. The slope stays the same. Now it's summer in the Southern Hemisphere, the days are longer and there's more light. It's winter in the Northern Hemisphere.
Milankovitch suggested that the tilt of the earth's axis is not always 23.5°. There are fluctuations from time to time. He calculated that the changes lie in the range from 22.1° to 24.5°, repeating this with a period of 41,000 years. When the slope is smaller, the temperature is lower than usual in summer and higher in winter. As the slope increases, more extreme climatic conditions are observed.
How does all this affect the climate? Even with increasing temperatures in winter, it is still cold enough for snow in areas far from the equator. If summers are cold, then it is possible that snow in high latitudes will also melt more slowly in winter. Year after year it will stratify, forming a glacier.
Compared to water and land, snow reflects more solar energy into space, causing additional cooling. From this point of view, there is a mechanism of positive feedback. Due to the decrease in temperature, snow accumulates additionally and glaciers increase. The reflection increases over time, and the temperature decreases, and so on. Perhaps this is how the ice ages began.
The shape of the Earth's orbit around the Sun
The second factor studied by Milankovitch is the shape of the Earth's orbit around the Sun. The orbit is not perfectly round. At certain times of the year, the Earth is closer to the Sun than usual. The Earth receives much more energy from the Sun, being as close as possible to the star (at the perihelion point), in comparison with the maximum distance (the aphelion point).
The shape of the earth's orbit changes cyclically with a period of 90,000 and 100,000 years. Sometimes the shape becomes more elongated (elliptical) than it is now, so the difference in the amount of solar energy received at perihelion and aphelion will be large.
Perihelion is now observed in January, aphelion in July. This change makes the climate of the Northern Hemisphere milder, bringing additional warmth in winter. In the Southern Hemisphere, the climate is more severe than it would be if the Earth's orbit around the Sun were circular.
Precession
There is another difficulty. The orientation of the earth's axis changes over time. Like a top, the axis moves in a circle. Such a movement is called precessional. The cycle of such a movement is 22,000 years. This causes a gradual change of seasons. Eleven thousand years ago North hemisphere was tilted closer to the sun in December than in June. Winter and summer changed places. After 11,000 years, everything has changed again.
All three factors: axial tilt, orbital shape, and precession change the planet's climate. Since this happens on different time scales, the interaction of these factors is complex. Sometimes they enhance the effect of each other, sometimes they weaken. For example, 11,000 years ago, the precession caused the beginning of summer in the Northern Hemisphere in December, the effect of increasing solar radiation at perihelion in January and decreasing at aphelion in July will increase the interseasonal difference in the Northern Hemisphere, instead of softening as we are now familiar with. Not everything is as simple as it seems, since the dates of perihelion and aphelion also shift.
Other factors affecting climate
In addition to the shifting effect of the Earth's motion, are there other factors influencing climate?