Why is the temperature difference between north and south big in winter in China?

Why is the temperature difference between north and south big in winter in China? Mainly related to the amount of sunlight and heat. In winter, the sun shines directly near the Tropic of Capricorn, and the land in the north of China just faces the sun obliquely, with short days and less light and heat from the sun; In the south, the inclination angle of the sun shining on the earth is much smaller than that in the north, and the ground gets much more light and heat from the sun, and the daytime is longer than that in the north, thus causing a great temperature difference between the north and the south. At the same time, the winter wind and cold wave from the northwest hit, "the sky is crisp and the cold current is urgent", and the northern part of China bears the brunt, and the temperature has dropped a lot. However, the winter wind and cold wave are weakened by the environment along the way in the process of going south, and the cooling effect is less when going south. This will further expand the temperature difference between north and south in winter.