We all have experienced: the closer we are to the furnace we feel hot, and it will get hotter and hotter; when we are away from the furnace, we feel less heat and cooler and cooler.
Earth orbit orbits the Sun in an ellipse. The distance between the Earth and the Sun is always changing. Astronomers tell us that every year, January 3 is the day the Earth is closest to the Sun, July 4 is the day the Earth farthest from the Sun. The Sun is a heat-generating sphere. In principle, the closer to the Sun, the hotter the temperature is; the hottest Earth period should be January, the coldest should be July. But in reality, January is the cold season, and July is the hot summer. Why is that?
The reason is that the heat and cold of the climate, although the heat absorbed from the Sun is more or less decisive when the Earth is close to the Sun, it is still not the main reason to decide how much or less heat is obtained. Because on January 3 every year, the Earth is about 147 million km from the Sun, on July 4, the Earth is 152 million km from the Sun. The distance between the Earth and the Sun of those two days is only two different % (about 5 million km), so the effect of heat obtained by the Earth is not very different.
The main reason for determining the warmth and cold of the climate on Earth is the tilt of sunlight on the ground. The greater the inclination, the less heat obtained per unit area on the ground. Winter sunlight shines on the Northern hemisphere completely tilted, plus long days and nights, so the climate is cold, and in summer, the sunlight is relatively perpendicular to the Earth, plus days and nights are short, so the weather is cold. The tail is very hot.
January is hot in the southern hemisphere, and July is cold. It was not actually because January the Earth was close to the Sun, July was far away, but it was still due to the more tilt of the sunlight to the southern hemisphere than in July.