Why is it hot in the Xisha Islands, but icy and snowy along the Heilongjiang River?

Because our country is so vast, it has different looks at the same time. According to the query of relevant public information, my country's territory spans a wide range of latitudes from north to south. Most of it is located in the mid-latitudes and belongs to the northern temperate zone. A few areas in the south are located in the tropics south of the Tropic of Cancer. There is no cold zone. The northern latitude is high, the southern latitude is low, and the northern latitude is low in winter. At noon, the height of the sun is small and the day is short, so less solar radiation heat is obtained and the temperature is low. In winter, the sun is higher at noon in the south and the day is longer, so it gets more solar radiation heat and the temperature is higher. The north is close to the source of the winter monsoon and is greatly affected by the winter monsoon. The temperature drops sharply. The winter monsoon intensifies the severe cold in the north. The south is far away from the source of the winter monsoon. When the winter monsoon travels south, it is blocked by numerous mountains, especially the east-west mountains. When it reaches the south, the force is very weak or can no longer affect the south. The temperature in the south is higher. Therefore, in winter, when the weather in the Paracel Islands is hot and the trees are lush, the coast of Heilongjiang is covered in ice and snow. The reason for this difference is that my country has a large latitude between the north and the south.