What influence does the revolution of the earth have on spring, summer, autumn and winter?

The four seasons on the earth are caused by the inclination of the earth axis and the revolution of the earth. The inclination between the earth's axis and the ecliptic plane is always 66-33 degrees. Therefore, when the earth revolves around the sun, the radiation and heat received by the northern and southern hemispheres are constantly changing, thus forming a continuous cycle of alternating cold and warm.

When the earth moves to the "summer solstice" position around June 2 1, the sun shines directly on the tropic of cancer. At this time, the northern hemisphere receives the most solar heat, that is, summer; Later, the sun gradually moved south, and the solar heat received by the northern hemisphere gradually decreased. By the "autumnal equinox" around September 23rd, the sun is facing the equator, and the light and heat received by the northern hemisphere are gradually equal. At this time, the northern hemisphere is in "autumn". After the autumnal equinox, the sun moved to the southern hemisphere. By the "winter solstice" around February 22, 65438, the sun will directly shine on the Tropic of Capricorn. At this time, the northern hemisphere receives less sunlight and heat, which is winter. Because the earth keeps spinning, spring, summer, autumn and winter also appear alternately.

The criteria for dividing the four seasons vary from country to country. For example, in China, the division is mainly based on astronomical factors. The six solar terms from beginning of spring to Grain Rain are spring; The six solar terms from long summer to great summer are summer; The six solar terms from beginning of autumn to the first frost are autumn; The six solar terms from beginning of winter to the Great Cold are winter.

Every quarter is three months. Take vernal equinox, summer solstice, autumn equinox and winter solstice as the middle periods of spring, summer, autumn and winter.

Western countries usually determine the four seasons by months: March, April and May are spring; June, July and August are summer; 9, 10, 1 1 three months is autumn; The month of 12, 1 2 is winter.

In addition, there is a method to divide the four seasons by astronomical factors, that is, the vernal equinox is the beginning of all the seasons, so it is spring from the vernal equinox to the summer solstice; From summer solstice to autumnal equinox is summer; From the autumnal equinox to winter, the solstice is autumn; It is winter from winter solstice to vernal equinox. But from all over the world, are there any seasons, such as the equator and the polar regions, that only exist in summer and winter?