Why is it so cold during the Spring Festival?

The first reason is that we are in a La Niña state this year, which is that the sea temperature in the eastern equatorial Pacific is below minus 0.5 degrees below normal, and this phenomenon has a great impact on China’s climate. Obviously, under the influence of the La Niña phenomenon, the meridional circulation in East Asia is abnormal. Such a circulation situation is very conducive to the southward movement of cold air from northern my country. It makes us have a cold winter, so we can see that this cold winter is coming this year. The second reason is that the two conditions that snow or rain must meet are 1. It comes from warm and humid airflow in the tropics. 2. There is cold air coming from alpine areas. Winter snowfall areas (the same applies to summer rainfall areas) are distributed near the front, which is the junction of cold and warm air masses. This position is not fixed and is determined by the strength of the two natures of the air masses. The cold air mass is weak, and the front and precipitation areas are at high latitudes. The cold air mass is strong, and the front and precipitation areas are at low latitudes. The land-based cold high pressure that affects my country in winter is the Asian High (also known as the Mongolian and Siberian High), which is centered in Mongolia and Siberia. Its sphere of influence is very large and has a great impact on the weather in my country, especially in the northern region. The cold air that affected our country in the early part of this year's midwinter was relatively weak and not frequent. Even with the combination of warm and humid airflow, it would not be easy to snow without cold air. However, since 2008, the Asian high pressure has been very active, continuously forming cold air masses moving southward to affect our country, causing large-scale windy and cooling weather. However, because the warm air masses in the south are also very active this year, a large number of warm and humid airflows from the Pacific and Indian Oceans frequently visit the southern region. When a powerful cold air mass from Siberia in Mongolia quickly moves southward to the southern region and meets the warm and moist air mass, the cold and the warm are perfectly combined. Due to the simultaneous influence of these two airflows, there have been more rain and snow weather in recent times, especially in the Yangtze River Basin, and low temperatures have been maintained for a long time.

If there is only a strong cold air mass without a large amount of water vapor provided by a warm and humid air mass, there will only be windy and cooling weather in the south; if there is only a large amount of water vapor provided by a warm and humid air mass but no cold air