How do the seasons change in different corners of the earth?

"All the year round" does not apply to every corner of the earth.

For us humans, a year is a long time, and it takes the earth to complete an orbit around the sun. If the word "year" is associated with astronomical mechanics, it is the so-called circular motion of the planet around the star. In contrast, it takes a shorter time for a satellite to orbit the planet in an orbit. For example, our moon's orbit around the earth is only one month.

It is the deviation angle between the earth's orbital plane and its rotation axis that reaches 23 degrees and 26 minutes, which leads to the seasonal variation of the earth at different times. We often say that there are four seasons in a year, but this statement is not correct in some parts of the earth. Then, why are there only two seasons in some areas? Why are the seasonal changes caused by the earth's rotation periodic and different?

Seasonal changes begin with the rotation of the earth.

When the earth leans towards the sun, the seasonal changes begin. When the earth revolves around the sun on an invisible axis of rotation, we call the point closest to the sun perihelion, and vice versa. The so-called ecliptic plane is the plane where the earth's orbit lies. It is precisely because the ecliptic plane and equatorial plane of the earth do not coincide, forming an intersection angle of 23 26' 21",so there are distinct seasons on the earth. Solstice in winter, vernal equinox, autumnal equinox and summer solstice are familiar solar terms. The vernal equinox and autumnal equinox are collectively called vernal equinox, which is one of the two intersections between the celestial equator and the ecliptic. Summer solstice and winter solstice are called two solstice points, which are the farthest points on the ecliptic and equator.

There is a time difference between the seasons in the southern hemisphere and the northern hemisphere.

People have just realized that the seasonal changes on the earth are essentially the direct result of the tilt of the earth's axis. Because the direction of the earth's axis is almost fixed in an orbit, in different parts of the orbit, one hemisphere of the earth is "tilted" to the sun (summer) and the other hemisphere is "tilted" to the sun (winter). In six months, the earth will tilt in the opposite direction. When summer comes, the tilt of the earth will cause the southern hemisphere to tilt towards the sun and the northern hemisphere to stay away from the sun in winter, and all this will reverse after six months.

For the position north or south of the equator on the earth, the main feature of each season is the change of temperature, which is caused by the difference of sunshine in the whole hemisphere during the earth's orbit in one year. For example, the hemisphere tilted to the sun will experience longer sunshine hours and more direct sunlight. In summer, because the sun in the sky is higher, the sunlight reaching the ground will be more concentrated; In winter, the position of the sun in the sky is low, which leads to the spread of the sun in a relatively large area; Speaking of spring and autumn, the two hemispheres receive roughly the same amount of sunlight.

At the equator, the annual temperature change is much smaller, and usually only two seasons are considered: dry and humid (or monsoon). For life in the Arctic and Antarctic, these two seasons seem to have only six months of long winter, followed by six months of long summer! In the Arctic Circle and Antarctic Circle (66.5 degrees north and south latitude), there will be at least one continuous 24-hour day and one continuous 24-hour night.

Because the earth's orbit is elliptical, the changing distance between the earth and the sun is often regarded as the main reason for seasonal changes. But this understanding is incorrect! The method from the nearest (distance from perihelion = 147090000 km) to the farthest (distance from apohelion = 152.65438+ million km) is only about 3% of the distance from the sun to the earth. This slight distance change can't explain the temperature difference in Xia Dong, let alone why one hemisphere of the earth is winter and the other hemisphere is summer.

Seasons are cyclical and different.

Like other things, seasons have two obvious characteristics. One is the periodicity of seasonal changes, and the other is the difference of seasonal changes. Because China is located in the temperate zone of the earth, people in most places can obviously feel the changes throughout the year. But in fact, the time a region experiences a season in a year mainly depends on which hemisphere the region is located in.

Perhaps, some people think that the north and south poles of the frigid zone only have winter, but they also have their own four seasons. There are only two seasons in a year in the savanna, because only two seasons are distinguished by rainfall: rainy season and dry season. At the same time, some places on the earth are summer or winter all the year round. For example, the annual average temperature near the equator is above 22 degrees Celsius, while the monthly average temperature at the poles of the earth is below 10 degrees Celsius.

Astronomical season is different from climatic season.

Simply put, places with spring-like seasons are generally distributed in low-latitude plateau areas or mid-latitude oceans. Because tropical and some subtropical regions have the characteristics of small temperature change, rainfall is used as an index to divide them simply. Objectively speaking, these two different ways of dividing seasons are actually the differences between astronomical seasons and climatic seasons. The definition of astronomical season is related to the orbital characteristics of the earth around the sun. Although it is completely based on the earth's rotation, it ignores the actual weather and geographical factors.

Climate season is mainly based on the distribution of regional climate elements, which can better serve human life and production activities and has great practical significance. Of course, due to the complexity of the weather process itself, there is no unified standard to divide the seasons. Moreover, due to the different location of each region, the influence of weather system on them may be different, so it is not mature to directly replace astronomical season with natural weather season. In a word, different latitudes on the earth have obviously different seasonal variation characteristics. Only by combining the astronomical season with the climatic season can we bring convenience to mankind.

The unique seasonal characteristics of the earth.

The gradual progress of time will bring obvious changes to our surrounding environment and weather. Although the attributes of the four seasons will vary from place to place, the four seasons are still widely defined as crossing most boundaries. Spring always represents the revival of everything and the rising temperature, which is generally considered to be a season from vernal equinox to summer solstice; Summer is the season with the highest temperature in a year, which is between spring and autumn. It is also the season with increasing rainfall and frequent forest fires.

In autumn, some plants on the earth will start to sleep, and the temperature will drop again, suggesting that animals need to start preparing for the coming winter. Autumn is a harvest season, and everything begins to wither. It is precisely because chlorophyll in leaves is sensitive to cold and light that such climatic conditions lead to the yellowing of leaves. Winter is the coldest season in a year. Many areas often face continuous snowfall, and animals often change their appearance in this season to adapt to the harsh external living environment.

In fact, the characteristics and timing of seasons mainly depend on the location of specific areas on the earth. For example, people near the equator need to experience hot summer, and people near the poles need to experience cold winter. In those areas near the equator, the average temperature in these areas is relatively stable all year round, because the sunlight they get is relatively constant on the curve outside the earth. From the visual experience, we feel the rich natural color changes in this world all year round; In terms of life, every weather has activities that are not suitable for other seasons: swimming at the seaside in hot summer and skiing in snow-capped mountains in cold winter, and we are located in this area where we can fully experience seasonal changes.