Why do the seasons change? Seasons on the planets of the solar system
You already know, young friend, that all planets circle the Sun in their own way. The time it takes for them to make a full circle is called a “year”. But the road for some planets is short, for others it is longer, some run faster, others much slower, therefore the year on each planet lasts a different time. The shortest year is on Mercury, and the longest on Pluto, the ninth planet of the solar system.
Few of the sun's rays reach it now, so the frost has cleared up, frozen the rivers and lakes, forced people to wear 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.
Please tell me how you spent this weekend? Did you ride a bike, sunbathe in the sun or play in the snow or make a snow woman? What clothes do you put on before going out?
It turns out that we do so many interesting things every day, depending on the time of year. In the summer we relax in nature, in the fall we collect a herbarium from leaves, in the winter we go ice skating and skiing, and in the spring we throw off our warm clothes and enjoy the gentle sun. Every season brings something different and new. Each season changes our lifestyle, type of clothing, affects walks and entertainment. Remember your school lesson on the topic of seasons in the subject of natural history.
A little complicated?
Then here: Seasons for children +3 to>7
Four Seasons:
The seasons consist of four seasons: summer, when the days are longest and the sun rises high above the horizon; winter - days are short and nights are long; the off-season seasons of spring and autumn, which account for the period of transition between the seasons of summer and winter.
(For temperate zone, central part of Russia)
Summer is replaced by cool autumn, then winter cold sets in and then the long-awaited spring thaw comes - and so on an infinite number of times, from year to year. What is the mystery of this natural phenomenon and why do seasons change on Earth?
To fully visualize the picture of how this happens, it is worth telling how the globe moves in space.
There are two of these movements:
- 1) The Earth around its axis (a conventional line passing through the center of the north and south poles) makes a full revolution per day. Thanks to this astronomical phenomenon, day gives way to night. When it is hot noon on the continents facing the Sun, it is deep night on the unlit continents.
- 2) The Earth moves along an elliptical path around the Sun, making a full revolution within 1 year.
What causes the change of seasons?
The Earth's orbit is elliptical, not circular, and in this orbit there is a point closest to the Sun (perihelion), where the Sun is approximately 147 million km, and the farthest point (aphelion 152 million km). This 3% difference in distance results in about a 7% difference in the amount of solar energy the Earth receives at perilegy and aphelion. However, there is a big misconception that closer to Earth towards the Sun, the warmer it is, and vice versa, the farther away, the colder it is. It is not right! Just at perihelion in the Northern Hemisphere, January falls, the middle of the coldest season of winter.
Interestingly, the position of the Earth has nothing to do with the changing seasons at all. The key role is played by the angle of inclination of the Earth's axis, which is 23.5°. As the Earth moves around the Sun during the year, either the Northern Hemisphere or the Southern Hemisphere is turned. It is on the hemisphere that is closest to the Sun that summer begins, since it receives 3 times more sunlight and warmth. And on the other, facing further from the Sun, and receiving less heat and hours of sunshine, at this time is running winter.
If there were no angle of inclination and the globe moved around the Sun in a strictly vertical position, there would be no seasons at all, since any points globe on the illuminated side the suns would be equally distant, as a result of which the air would warm up evenly.
What does the change of seasons look like for the northern hemisphere?
Summer
As the Earth moves throughout the year in orbit, the northern hemisphere, due to the angle of its axis, is located closer to the Sun and the summer season begins there. Daylight hours increase in duration, and in areas located closer to the pole, even at midnight it is light outside.
Winter
Further, in the process of moving along its orbit, the Earth finds itself on the other side in relation to the Sun, and now the angle of inclination removes the northern hemisphere from the warm rays of the sun and winter sets in there. The dark time of the day increases, and daylight hours become short. At this time, summer comes to the continents of the southern hemisphere.
This is what the change of seasons looks like on the continents of the Earth:
It is interesting that residents of the equatorial and tropical zones know about the onset of cold weather from hearsay. Here, seasonal changes occur so smoothly that they are practically not felt, because the equator, regardless of the position of the planet in its orbit, is almost always equally distant from the Sun.
Equinox periods:
- The vernal equinox- March 20 - 21. The sun moves from the southern hemisphere to the northern.
- Autumn equinox- September 22 - 23. The sun moves from the northern hemisphere to the southern.
This is why the seasons in the Northern Hemisphere are opposite to those in the Southern Hemisphere. During the period between the months of March and September during the day most time, the Northern Hemisphere faces the Sun and receives more heat from the sun's rays than the southern hemisphere of the earth. This is the period of summer in the Northern Hemisphere when the days become longer and the nights become shorter.
After six months, the position of the earth towards the sun changes, but the inclination remains. Now, in the southern latitudes of the Earth's hemisphere, the days are becoming longer, and the sun is rising higher, while in Northern latitudes winter is coming in the hemisphere. This cycle of time throughout the year is enough to heat or cool certain areas of the planet. This is why the seasons gradually change and are divided into seasons.
The earth consists of climatic zones, which correspond to a certain climate. This is due to various physical properties the surface of the earth and water in various parts of the globe. Therefore on different continents climatic seasons begin differently in relation to the astronomical seasons.
So, on one continent, snow may fall in winter, and rain in summer, and on another continent there may be no snow or rain at all for a long period of time, but the season of heavy rains will fall on a strictly defined season of the year.
Climate zones on Earth:
- Equatorial belt- spring and autumn are characterized by dry seasons, while summer and winter are characterized by increased rainfall.
- Tropical zone - stays dry most of the year, hot weather and only once a year, during the rainy season, does it fall a large number of precipitation. This season is also a relatively cold season of the year.
- Temperate zone (Western Europe, Central Russia) spring and summer are relatively dry with short-term precipitation, autumn and winter are characterized by a lot of precipitation and stable snow cover.
- Arctic and Antarctica- seasons change only in the form of a change in the polar day and night, changes weather conditions practically undetectable and the temperature always remains below zero.
And this is how the Norwegian photographer Eirik Solheim saw the seasons, combining the footage taken from the same place in 40 seconds unique video changes of seasons:
(One year in 40 seconds. Eirik Solheim)
A unique video about the change of seasons. All seasonal changes nature for a whole year in just 40 seconds. The author took one photograph almost every day for a year, the result was the reduction of an unusual experiment into a short video that clearly demonstrates how nature changes through all four seasons.
Let's summarize: Summer comes at the moment when the hemisphere in which we live is more facing the Sun and receives more heat, and when the Sun shines less in our hemisphere, then winter comes. This does not depend on the distance of the Earth from the Sun, but occurs due to the tilt of the Earth's axis at 23.5°.
Even in childhood, we notice that nature around us is constantly changing. It’s hot and sunny outside, the greenery is lush and we know that it’s summer. But then a month passes, then another, and it becomes cooler, leaves begin to fall, and it rains. It's autumn. After autumn comes snowy winter, which, in turn, gives way to spring, when the snow melts and streams run. And then summer comes again. Why does the season change? Let's try to figure it out.
Our planet Earth, which is spherical in shape, revolves around a star called the Sun. Full turn The Earth makes exactly one year around the Sun. At the same time, the Earth also rotates around its axis, making one revolution per day. It is due to rotation around its axis that the change of day and night occurs on Earth.
The points through which the Earth's rotation axis passes are called poles. In the Northern Hemisphere, this point is called the North Pole and it is located in the Arctic Ocean, and in the Southern Hemisphere there is the South Pole, which is located on a continent called Antarctica.
Astronomers have long discovered that the Earth's axis is tilted relative to the plane in which the Earth rotates around the Sun. Due to this tilt of the earth's axis different times The height of the sunrise above the horizon varies throughout the year. For example, in the summer the Northern Hemisphere is tilted towards the Sun and you can notice that at noon the Sun is high above your head, almost at its zenith. At the same time, the Sun warms the surface of the Northern Hemisphere so well that summer comes there and all nature blossoms. In summer the days are very long and the nights are short. And in areas close to North Pole In summer the sun does not set beyond the horizon at all and polar day sets in.
When the Earth makes another half revolution around the Sun, the Northern Hemisphere will be tilted in the direction opposite to the Sun, and winter will come. The sun will rise very low above the horizon. The day will become short and the night will be long. Due to the short daylight hours and the low altitude of the Sun above the horizon, the surface of the Northern Hemisphere warms up poorly and winter sets in. In the polar regions, in winter there is a polar night, when the Sun does not rise above the horizon at all.
In the Southern Hemisphere, everything happens exactly the opposite - in June, July, August there is winter and snow, and in December, January, February, summer begins.
In intermediate positions of the Earth between “winter” and “summer”, when Northern and South pole equally distant from the Sun, spring or autumn periods begin, depending on the hemisphere. In autumn and spring there are two special days when day is equal to night. Such days are called equinox days.
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 moderate climate 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 earth's surface relative to the ocean, terrain 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, which is most pronounced 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 summer - reaches for a right angle. But it doesn't reach. Full 90° can only be fixed at the equator. And at the poles Sun rays they simply glide, limited to a maximum angle of incidence of 27-30°.
For the temperate zone, the time when the planet is as close and inclined to the Sun as possible 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".
