What time of year is it now? Why is there winter and summer? A story about the process of changing seasons for children

How boring it would be to live if the frosty winter were not replaced by a young and tender spring, if it were not replaced by summer with vacations and fresh fruit and vegetables, and velvet autumn is generally loved by many people for its tranquility and beauty. We accept all seasons, enjoy them, and rarely think about why the seasons change. This turns out to be complicated natural phenomenon, based on the location of the planets - the Sun and Earth.

Annual circle of the Earth

If we talk about the change of day and night, then it is much easier to understand. The Earth turned to the Sun as your city, it’s day for you, it turned away, you look into dark space - it’s night for you. The Earth rotates around its axis in 24 hours. The reason for the change of seasons is that, in addition to this rotation, the Earth makes a circular path around the Sun. She completes this circle in 365 days and 6 hours, this time period is called a year. Over 4 years, 4 times 6 hours are accumulated, and appears in the calendar leap year, which has 366 days.

How do the seasons change?

The thing is that the Earth is in the orbit of the Sun not directly, but at an angle, the axis of the Earth and the orbit of the Sun form an angle of 23 degrees 27 minutes. And it turns out that one hemisphere is always closer to the Sun, and the second is further away. Therefore, one is summer, and the other is winter. It should be noted that in order for summer to come, the rays of the Sun must hit the Earth at right angles. When the Earth turns toward the Sun at a tangential angle, it turns out that the distance to the southern and northern hemispheres is the same, then spring and autumn begin. There are two days in a year when day is equal to night, and in the northern and southern hemispheres these parts of the day are compared. This occurs around September 23rd and March 21st. It is always summer at the equator, because the distance to the sun does not change here, the rays are always direct, and they provide the heat. There are places where it is always winter for the same reason. The sun's rays very rarely hit the Earth's poles at right angles, only tangentially. And, as we know, sliding rays cannot melt ice, they only illuminate the Earth. Only one thing always remains stable - the tilt of the Earth's axis, it is always directed towards the North Star, which always points to the north.

Model of the Earth and the Sun

To better understand how the seasons change, you can make your own model of the Earth and the Sun. Take a table lamp and place it in the center of the table. Now take an old ball and pierce it with a regular knitting needle strictly in the center. This is how we clearly marked the axis of the Earth. Tilt the axis approximately 23-25 ​​degrees, do not jerk your hand or change the direction of the axis. The more illuminated half of the ball from above? So it's summer there now. Now rotate the ball, move it 90 degrees. The previously bright half became equally illuminated as the other half. Therefore, autumn has come here. Now move another 90 degrees, our half of the ball has become darkened. It's winter here now, the rays of the lamp only fall on her in passing. After the next 90 degrees, our half will be lit a little brighter, and, returning to its previous position, it will again become the lightest. It's been a whole year!

The root cause of everything

This is how the world around us works, the change of seasons is a brilliant idea of ​​nature, of the Universe. It is this that ensures balance in space, causes not only the seasons to change, but also water to circulate on the planet, volcanoes to erupt, and currents to move in the ocean. Everything on Earth happens precisely because of this, namely, the forces that ensure interaction between the planets, and in our case, between the Earth and the Sun.

You already know young friend that all planets orbit the Sun in their own way. The time it takes them to do full circle, is called "year". But the road for some planets is short, for others it is longer, some run faster, others much slower, that’s why the year on each planet lasts different times. Most short year– on Mercury, and the longest on Pluto, the ninth planet solar system.

Few sunlight reaches it now, so the frost has cleared up, frozen the rivers and lakes, forced people to put on warm clothes. But the southern hemisphere faces the Sun, it gets a lot of heat and light, so it’s summer there.

But the Earth does not stand still - it runs without stopping in its orbit, gradually the northern hemisphere turns towards the Sun, the Sun warms the earth more and more nm, the snow melts, the grass turns green, the first leaves appear - spring is coming!.. And in the southern hemisphere, with every The day is getting cooler and autumn is just around the corner...

But the planet continues its path around the Sun. We're already halfway there. Look at the drawing, see? The southern hemisphere has completely “turned away” from the Sun. This means that winter has come there, and here it is summer!

And in three months the Earth will run another quarter of the way and again it will get colder in our northern hemisphere, autumn will come into its own, and in another three months it will be again New Year! The earth will run a full circle and begin a new, next year.

The reason why the seasons change on Earth is the presence of an angle of inclination relative to the axis. Because of it, the hemispheres approach the heat source one by one as the planet rotates around the Sun. On the half that receives most of the heat celestial body Summer comes, and the other during this period warms up 3 times less, which leads to the onset of winter.

Due to the tilt of the planet's rotation axis, its Northern and Southern hemispheres alternately approach the Sun. The closer to the Sun, the warmer it is. Credit: NASA/JPL-Caltech/quibbll.com.

Why do seasons change?

In ancient times, people explained the changing seasons of the year using mythology. Only during the Renaissance was it proven that the planet has the shape of a ball and revolves around the Sun. Then the version proposed by religions was refuted.

When moving in orbit, the Earth either approaches the Sun or moves away from the celestial body. The distance between the bodies varies from 147.1 to 152.1 million km. At the same time, at the beginning of June the Earth moves away as far as possible, and at the beginning of January it approaches the star. The change of seasons of the year is not explained by the movement around the celestial body. Many adults do not know this fact.

Winter and summer alternate due to the fact that the planet warms up unevenly. Since the angle of inclination of the axis relative to the Sun is 23°, per hemisphere sun rays hit at a right angle, and the second - at an acute angle. During the revolution, first one area is better illuminated, then another due to a change in position relative to the Sun. One hemisphere receives most of the heat. Summer days are coming there. At the same time, the winter cold comes in the opposite direction.

At the equator, where direct sunlight always hits, the change of seasons occurs more gently, there is no snow and freezing temperatures. The further the climate zone is from the equator, the greater the changes in weather conditions.

If there were no tilt angle, the Earth would warm up at the same rate all year round. Seasons would not arise in such a situation. There would be permanent summer at the equator, and as we moved away from it the weather would gradually become colder.

Weather conditions would be constant even in the absence of orbital movement. In such a situation, one hemisphere would be constantly illuminated better than the other, and eternal summer would be observed there. It would always be cold on the opposite side of the planet.

You can familiarize yourself with the mechanism of changing seasons in the diagram.

Calendar seasons

The year is divided into 4 seasons:

• winter;
• autumn;
• spring;
• summer.

In winter, daylight hours are shortened and temperatures drop. The amount of precipitation may increase. Snow falls in most regions of Russia, and negative temperature. In areas with a milder climate, the cooling is not so strong; prolonged rains and downpours are possible.

Autumn and spring represent transitional states between summer and winter. Weather conditions during these periods they gradually change. In spring it gradually gets warmer, and in autumn, on the contrary, it gets colder. The nature of precipitation is also changing. IN spring months Daylight hours become longer; in autumn their duration decreases.

Summer length daylight hours greatest. The air temperature also increases. In areas near the poles dark nights may be completely absent. It's light there all day long. Snow it's summer only in areas close to the poles. In the southern hemisphere, summers are warmer as the planet moves closer to the Sun during this period.

Each season takes 3 months. When they are completed, the seasons change.

The higher the Sun is above the horizon, the more solar heat falls on the same area of ​​the Earth's surface. Credit: artlebedev.ru/quibbll.com.

Astronomical seasons

The beginning of the astronomical seasons is considered to be the days on which the center of the Sun passes through the solstices or equinoxes. There are 4 of them in total, as well as calendar seasons.

Astronomical summer lasts from summer solstice(June 21) until the autumnal equinox (September 23). It takes 93 days 14 hours and 24 minutes.

Then comes autumn, lasting until December 22 - the date winter solstice. It lasts 89 days 18 hours and 42 minutes.

After follows lasting until spring equinox(March 21) winter. The length of this season is 89 days and 30 minutes.

Spring ends with the summer solstice. Its duration is 92 days 20 hours and 12 minutes.

Equinox periods

Equinoxes are periods when the length of daylight is approximately equal to the length of night. Every year there are 2 such days. In the spring, the equinox falls on March 20-21, and in the fall - on September 22-23.

Solstices are the days with the longest daylight and longest night.

Climatic seasons

Because of physical properties liquids and soils climatic seasons change later than astronomical ones and do not coincide with calendar ones. The duration of delays depends on the climate zone. The further from the equator, the more different summer and winter are.

At and near the equator, summer and winter are characterized by large amounts of precipitation and prolonged rains. In spring and autumn, humidity decreases and showers disappear. Temperatures near the equator are always high. It never snows here.

In the tropics winter months rainy, and summer - hot and dry. In deserts, it rains infrequently even in winter. All year round the temperature here is above 0°C.

Possible in the temperate zone various options for the seasons. This is explained by the proximity of the ocean, warm or cold currents. In Europe, conditions are milder than in Siberia due to the proximity of the Gulf Stream. Temperatures don't drop too low in the United States either.

In the temperate continental climate zone, most of the moisture occurs in the summer. Winter is dry and cold. In the oceanic region, rain and snow occur more often in winter and autumn, and in summer and spring the amount of precipitation decreases. Monsoon climate, characteristic of Far East, characterized by heavy rainfall in summer at almost complete absence precipitation in winter.

The Arctic and subarctic climate zones are characterized by a change in polar day and night. Most of the time, the sun's rays do not reach this area, which is why it is dark around the clock. Permafrost is observed. Even in summer the temperature does not rise high, the earth does not warm up. Seasonal fluctuations in precipitation are weak.

Moving to outer space,The Earth undergoes four types of motion. It rotates along with the Solar System around the center of the Galaxy. Our planet, together with the Solar System, completes one such revolution, called a galactic year, in 280 million years.

The influence of this movement on the processes occurring on Earth has not yet been studied. The Earth rotates around the Sun at a speed of approximately 30 km/s in an elliptical orbit at an average distance from the sun of 150 million km. If you imagine the incredible thing that the Sun suddenly stops attracting the Earth, then our planet will rush into space at a speed of 30 km/s.

The planet completes one revolution around the Sun in 365.24 days. This time is called the sidereal year.

The Earth's axis is constantly inclined to the orbital plane along which the planet moves, at an angle of 66°33`22″. The axis does not change its position as the Earth moves, so different areas throughout the year earth's surface receive unequal amounts of light and heat. The tilt of the earth's axis and the revolution of the earth around the sun cause the change of seasons.

The Earth rotates around its axis, making a full revolution in 23 hours 56 minutes and 4.1 seconds - a sidereal day. Thanks to this movement, the change of day and night occurs on the planet.

Together with your natural companion- , the mass of which is commensurate with the mass of our planet, the Earth rotates around a common center of mass with the Moon, making one revolution in 27 days and 8 hours. The Earth and Moon are considered a double planet. In the Solar System, only Pluto has a satellite - Charon, whose mass is comparable to the mass of this planet. Most planets in the Solar System have several satellites, and their masses are much smaller than the masses of the planets themselves.

Change of seasons

From June to August the Earth is in such a position relative to the Sun that Northern Hemisphere is illuminated more and receives more heat. At this time, the earth's axis is tilted with its northern end towards the Sun and it is summer in the Northern Hemisphere. June 22 - the day of the summer solstice - The sun is at its zenith over the Northern Tropic. IN Southern Hemisphere from June to August is winter, because the southern end of the earth's axis is tilted away from the Sun. The southern hemisphere seems to have turned away from the sun and therefore receives less heat and light. At this time there is a polar night beyond the Antarctic Circle.

The Earth is constantly moving in its orbit around the Sun. On September 23, the day of the autumnal equinox, the Sun is at its zenith above the equator, in the Northern Hemisphere it is autumn at this time, and in the Southern Hemisphere it is spring. Both hemispheres are illuminated evenly and receive the same amount of heat.

By December, the Earth finds itself on the other side of the Sun - on the opposite side of its orbit. Now the hemispheres seem to change places: the southern end of the earth's axis faces the Sun and it is summer in the Southern Hemisphere. On December 22, the day of the winter solstice, the Sun is at its zenith over the Southern Tropic.

On the day of the vernal equinox - March 20-21, the Sun again stands at its zenith above the equator, day is equal to night and the hemispheres are evenly illuminated and heated. Then the days in the Northern Hemisphere begin to lengthen, and in the Southern Hemisphere they begin to become shorter.

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The change of seasons that is familiar to us does not occur everywhere. They don't talk about this at school, but the fact remains. The four periods into which “our” year is conventionally divided can be distinguished only within the temperate climatic zone. In others geographical zones The picture of alternating weather cycles is greatly simplified.

For example, in the equatorial climate zone the weather is the same all year round - average daily temperatures are 24°C, and the amount of precipitation depends on the location of a particular area of ​​the earth's surface relative to the ocean, topography and prevailing winds.

In the tropical climate zone there are 2 seasons - dry and hot, and then dry and very hot. In Antarctica it’s the same thing, only in a different key. Cold and dry and very very cold and dry seasons. Thus - Seasons are available only to residents of temperate climate zones in both hemispheres, as well as in the adjacent sub-belts - subtropical, subarctic and subantarctic, but in a more blurred and leveled version.

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Why do the seasons change?

The main reason for the change of seasons is the rotation of the Earth around the Sun. Another key reason that manifests itself most in temperate latitudes, is the characteristic tilt of the earth's axis. In relation to the plane of the ecliptic, it is at an angle of 66.56°.

Therefore, it is at this latitude that we see the most complete, full-blooded and vibrant change of seasons, the days of the solstice, equinox, polar day-night.

Due to the tilt of the earth's axis, the sun rises above the earth at different angles throughout the year. In winter the angle is sharper. In the summer - reaches out to right angle. But it doesn't reach. Full 90° can only be fixed at the equator. And at the poles, the sun's rays simply slide, limited by the maximum angle of incidence of 27-30 °.

For temperate zone the time when the planet is as close as possible and inclined to the Sun will be called “summer”. It is distant and deviated along the axis from the plane of the ecliptic - “in winter”. The rule applies only to one hemisphere. Transient processes between two extreme points called "autumn" and "spring".