Why is the climate so abnormal in recent years?

There are two reasons. The first reason is that we are in a La Ni? a state this year, that is, the SST in the equatorial eastern Pacific is below minus .5 degrees lower than normal, and this phenomenon has a very obvious impact on the climate in China. Under the influence of La Ni? a phenomenon, the meridional circulation in East Asia is abnormal, and such a circulation situation is very conducive to the southward movement of cold air in northern China. It makes us have a cold winter, so we can see that this cold winter has appeared this year. The second reason is that there are two conditions that must be met when it snows or rains: 1. Warm and humid air flows from tropical areas. 2. There is cold air from the alpine region. The snowfall area in winter (the same as the rainfall area in summer) is distributed near the front, that is, the junction of cold and warm air masses. This position is not fixed, it is determined by the strength of two kinds of air masses. The cold air mass is weak, the front and precipitation area are high latitude, the cold air mass is strong, and the front and precipitation area are low latitude. The land cold high that affects China in winter is the Asian high centered in Mongolia and Siberia (also known as Mongolian and Siberian high), which has a very large sphere of influence and has a great impact on the weather in China, especially in the northern region. The cold air affecting our country in the early winter this year is relatively weak, and the frequency is not much. Even with the cooperation of warm and humid airflow, it is not easy to snow without cold air. However, since 28, the high pressure in Asia has been very active, and cold air masses have been formed southward, affecting China, resulting in a wide range of windy and cool weather. However, due to the active warm air masses in the south this year, a large number of warm and humid air streams from the Pacific Ocean and the Indian Ocean frequently patronize the southern region. When the powerful cold air masses from Mongolia and Siberia quickly moved southward to the southern region and met with the warm and humid air masses, the cold and the warm air were just combined. Affected by these two air currents, there have been more rainy and snowy weather recently, especially in the Yangtze River basin, and the low temperature weather has been maintained for a long time. If there is only a strong cold air mass without a large amount of water vapor provided by warm and humid air mass, there will only be strong winds and cool weather in the south; If there is only a large amount of water vapor provided by warm and humid air mass, and there is no cold air mass coming, there will be no disastrous weather at all. And when both are ready, disaster comes.