What is the strange cause of the snowstorm in 2008?

The first reason, La Nina phenomenon, is that the SST in the equatorial eastern Pacific is below minus 0.5 degrees lower than normal, which has a very obvious impact on China's climate. Under the influence of La Nina phenomenon, it is very conducive to the southward movement of cold air in northern China, so it will make us have a cold winter.

The second reason is that snow or rain must meet two conditions:

1, a warm and humid air flow from the tropics.

2. Cold air from cold regions. Since the beginning of 2008, Asian high pressure has been very active, and cold air masses have formed southward, affecting China. However, because the heating group in the south is also very active this year, the cold and warm are just together. Therefore, especially in the Yangtze River basin, there are more rainy and snowy weather, and the low temperature weather lasts 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. When both are ready, disaster comes.

Meteorologists said that the persistent low temperature in South China is closely related to La Nina phenomenon and abnormal atmospheric circulation. Experts pointed out that in the middle and high latitudes of Europe and Asia, a blocking high pressure appeared at high altitude and lasted for a long time, and the polar vortex remained motionless in Siberia, which led to the continuous invasion of China by cold air from the north.

At the same time of the cold air attack, the warm and humid air currents from the Indian Ocean and the western Pacific Ocean are continuously transported to South China, and the cold and warm air currents meet in the southwest, Jianghan, South China, Jiangnan, Jianghuai and other places, resulting in rare long-term and wide-ranging low-temperature rain, snow and freezing weather. However, experts stressed that the rare snow disaster in China was caused by many factors, and La Nina was not the only one.