Why is it hot and cold? What caused it?

The formation of the four seasons is the result of the earth's revolution around the sun. The earth keeps spinning from west to east, and at the same time it goes around the sun. The orbit of the earth's revolution is an ellipse, and the sun is always in a focus. In the process of the earth's revolution, the included angle between the earth's axis and the revolution orbit will always be 66 34', that is, the earth will always revolve around the sun obliquely. Because of the revolution of the earth, the direct point of the sun changes on the surface of the earth.

Every year around June 22nd, the earth is at apohelion. The sun will shine directly on the Tropic of Cancer, which is the summer solstice in the northern hemisphere. At the same time, the northern hemisphere gets the highest heat, the longest day and the hot climate. Summer belongs to the northern hemisphere, but the southern hemisphere is in a cold winter.

After that, the direct point of the sun will move south because it continues to run in the orbit of revolution. The sun will shine directly at the equator on September 23rd, which is the autumn equinox in the northern hemisphere. Now the sun's heat in the southern hemisphere and the northern hemisphere is equal, and it is equally divided day and night. It is autumn in the northern hemisphere and spring in the southern hemisphere.

The earth continues to run. By about 65438+February 22, the earth began to be at the perihelion, and the sun was directly on the Tropic of Capricorn. This day is the winter solstice in the northern hemisphere. At this time, the northern hemisphere gets the least heat, the shortest daytime and the climate is quite cold. This is winter in the northern hemisphere. It's summer in the southern hemisphere.

After the sun's direct point returned to the north, on March 2 1 day, the sun directly pointed to the equator again. This day is the vernal equinox in the northern hemisphere. At this time, it is spring in the northern hemisphere and autumn in the southern hemisphere. Like this, the earth revolves around the sun in a one-year cycle, causing the seasons to change.