Why is there no winter at the equator? Why is it cold in winter and warm in summer? geographic reasons for the change of seasons

Why are there seasons?

The change of seasons is an eternal and unchanging phenomenon of nature. The reason for it is the movement of the Earth around the Sun.

The path along which in outer space moves Earth, has the shape of an elongated circle - an ellipse. The sun is not at the center of this ellipse, but at one of its foci. Therefore, throughout the year, the distance from the Sun to the Earth periodically changes: from 147.1 million km (at the beginning of January) to 152.1 million km (at the beginning of July). The transition from the warm season (spring, summer) to the cold season (autumn, winter) does not occur at all because the Earth either approaches the Sun or moves away from it. And yet many people think so today! Take a look at the numbers above: the Earth is farther from the Sun in June than it is in January!

The fact is that the Earth, in addition to revolving around the Sun, rotates around an imaginary axis (a line passing through the North and South Poles). If the Earth's axis were at right angles to the Earth's orbit around the Sun, we would have no seasons and all days would be the same. But this axis is tilted with respect to the Sun (by 23°27"). As a result, the Earth revolves around the Sun in an inclined position. This position is maintained all year round, and the axis of the Earth is always directed to one point - to the North Star.

Therefore, in different time Years The Earth substitutes in different ways sunbeams its surface. When the sun's rays fall vertically, directly, the Sun is hotter. If the sun's rays fall on earth's surface at an angle, they heat the earth's surface weaker.

The sun always stands directly on the equator and in the tropics, so the inhabitants of these places do not know the cold. There is not as sharp as ours, the seasons change, and it never snows.

At the same time, part of the year, each of the two poles is turned towards the Sun, and the second part is hidden from it. When North hemisphere turned to the Sun, in countries north of the equator - summer and the day is long, to the south - winter, and the day is short. When the direct rays of the Sun fall on the Southern Hemisphere, summer comes here, and winter in the Northern Hemisphere.

The longest and shortest days of the year are called winter and summer solstice. The summer solstice occurs on June 20, 21 or 22, and the winter solstice on December 21 or 22. And all over the world every year there are two days when the day equals night. This happens in spring and autumn, exactly between the solstice days. In the fall, this happens around September 23 - this is autumnal equinox, in the spring around March 21 - the vernal equinox.

By the way...

In hot countries, there is also a change of seasons, it is only expressed in a different way, not like ours, in the middle latitudes.

In India, winter is a time of severe drought, from which all living things suffer. At this time, the winter monsoons blow - from land to sea. In the spring, the monsoons change direction, they begin to blow from the sea to the land, bringing with them abundant moisture, saturating the dry, thirsty land with moisture. Nature comes to life. The rainy season is coming. And the rains are pouring down there like from a bucket - not in separate streams, but in a continuous stream!

The seasons differ little from each other in Far North- in the Arctic, or in the Far South - in the Antarctic. It's always winter there. There is never real heat, and the snow only thaws from above in some places, exposing the frozen ground. The difference between winter and summer lies in the amount of light, not heat. In spring and summer, the Sun walks across the sky all day and night, does not fall below the horizon, but although its rays shine well, they warm poorly: they fall obliquely, as if sliding over the surface.

And yet under the high northern latitudes there is something similar to our spring and summer, in some places even modest northern flowers bloom, and on rocky islands northern seas nesting seabirds.

It is winter in Antarctica at this time, severe frosts and winds. There is a polar night. In summer, the sun comes there, and there it shines day and night, but the heat does not increase from this. In the southern hemisphere under high latitudes the climate is much harsher than in the North. The temperature never rises above zero.

I love the humorous remarks that are found on the Internet when the season "does not fulfill its function." For example, when it is warm in December and very cold in spring, sparkling humor is appropriate:

“Marry me to work, please,” March asks December.

- Oh sure. You married me, ”December agreed amicably.

But seriously, why does nature endow us with such a variety of weather? Let's understand in order what's what.

The fundamental reason for the change of seasons on planet Earth

Our planet moves around the sun along the ecliptic (an elliptical orbit). Axis, which, as it were, “pierced” two poles, in relation to the orbit is inclined at an angle of approximately 23 degrees. Therefore, the sun's rays unevenly fall on the two hemispheres of the Earth during the movement of the planet - this is the root cause of the change of seasons. Let's see how this happens:

If the Northern Hemisphere is more turned towards the Sun, then summer comes in the part of the Earth from the North to the equator, and winter comes in the Southern part. At the same time, the Earth is in highest point on the north side of the ecliptic.
When, moving in orbit, the planet "substitutes" the southern hemisphere for the sun's rays, then summer comes there, and winter - in the opposite part. The planet is at the lowest point of the ecliptic on the south side.
The first day of spring comes at a time when the Sun crosses the celestial equator from the Southern to the Northern Hemisphere.
The beginning of autumn is accompanied by the transition of the Sun from the Northern celestial hemisphere to the Southern one.

Determination of the season: astronomical method

In nature, winter, spring, summer or autumn does not come just because the calendar created by people has the 1st number :). In astronomy, the days of the winter solstice (December 21-22), summer (June 20-21), as well as the spring equinox (March 20-21) and autumn (September 22-23) are taken as a reference point.

Interestingly, these days in different countries often coincide with revered holidays. And in ancient times, on the days of the solstice and equinox, all kinds of rites and magical rituals were performed.

Winter occurs in some parts of Africa, but not in all. She comes there in the summer. While we are warm, there snowing. This is due to the fact that Russia and Africa are on opposite sides of the globe. When the globe rotates on its axis, one side of it looks at the sun, and the other side is in the shade. On that part of the land, which is currently closer to the sun, spring and summer occur, and on the remote part, autumn and winter come.

On the African continent There are two tropical zones - northern and southern. Their climate is different. The warmest and most stable weather is in that part of the land that is closer to the equator. At the equator, the weather is always stable. In those parts of Russia that are close to zero latitude, snow also does not fall in winter. For example, it is not in the city of Sochi. At the equator during the year there is only tropical air mass and there is no change of seasons. Summer is very hot, and in winter it is usual warm weather. AT tropical zone the pole of heat is located, that is, the hottest place on the planet. For example, near the city of Tripoli, the capital of the state of Libya, the air temperature was +58°C in the shade. It was not possible to measure the temperature in the sun, because there were not so many divisions on the thermometer. In the desert, consisting of sand, the air is very dry. During the day, the surface of the earth heats up quickly. Between day and night air temperature in one day there can be a difference of 20 degrees. Therefore, camel travelers usually travel at night and try to get from one staging post to another before sunrise.

There is another difference between the tropical climate in the southern and northern hemispheres of Africa. On the southern part the continent is blown by trade winds coming from indian ocean, and to the north - air from Eurasia. The trade winds don't change tropical climate in the northern part, and in the southern part they carry precipitation. Therefore, rain and snow are more likely to fall in the Southern Hemisphere.

Usually real winter with snow and stable cold temperature occurs only on the tops of the mountains and plateaus of Africa. At this time, animals living in cold areas begin to roam to other areas. The reason is that when the land dries up, then herbivores like zebras have nothing to feed on. According to eyewitnesses, the strings of animals stretch for tens of kilometers. After the cold has passed, they return as our migratory birds.

Nothing to wear? Winter will soon come into its own. If you have not had time to get winter outerwear, your attention is women's fur coats. A wide selection of great quality coats at an affordable price.

The summer solstice is an important astronomical and geographical event that takes place in solar system. At the moments of the solstices, the Sun, in its visible movement along the ecliptic, it is farthest from the celestial equator, reaches the greatest declination, north or south.

The points on the ecliptic that are farthest from the celestial equator through which the sun passes are called the solstice points. This is such a moment in the annual rotation of the Earth around the Sun, when the shortest day or the shortest night is observed.

There are summer and winter solstices. In the northern hemisphere, the summer solstice usually falls on June 21st and the winter solstice on December 21st. southern hemisphere- vice versa.

During the summer solstice, the Earth, as a result of the inclination of its axis to the plane of the ecliptic by 23 degrees, is turned towards the Sun. north pole. At the south pole at this time there is a polar night.

The day of the summer solstice is the day of the beginning of summer in the northern hemisphere of the Earth and the beginning of winter in the southern hemisphere (Argentina, Australia and Antarctica).

In middle latitudes, during the year in spring and early summer, the Sun rises higher and higher above the horizon every day, and at the time of the summer solstice it stops and reverses its movement. Then every day it goes down and, in the end, at the time of the winter solstice, it reverses its movement again and begins to rise.

During several neighboring days of the solstice, the Sun hardly changes its declination, its midday heights in the sky are almost unchanged; hence the very name of the solstice.

During the summer solstice in the northern hemisphere of the Earth, the Sun remains above the horizon for the longest time, June 21 and 22 are the most long days a year, and from 21 to 22 June - the shortest night.

The summer solstice has long been an occasion for celebration. The summer solstice is one of the most important holidays in life it was revered by the ancient Slavs and the Baltic peoples. Ivan Kupala Day was celebrated in Russia, in Lithuania it is known as Lado, in Poland - as Sobotki, in Ukraine - Kupailo, in Belarus - Kupala. Americans and Canadians consider this date the beginning of summer, the Chinese, Irish, Japanese, British - its height.