Snowfield weather

The abnormal atmospheric circulation under La Nina phenomenon is the "culprit" of snowstorm.

"The direct cause of the recent rain and snow weather is abnormal atmospheric circulation," said Sun Jun, chief forecaster of the Central Meteorological Observatory.

He analyzed that from the evolution of atmospheric circulation in the short and medium term, there have been frequent cold air and active warm and humid airflow since the winter of this year. Especially since June+10 in 5438, the circulation in the middle and high latitudes is mainly meridional, with frequent cold air activities. In addition, the subtropical system is strong, northwest than normal, which is conducive to transporting warm and humid air from the south to the north. On the one hand, the cold air in the north is very active, on the other hand, the warm and humid airflow in the south is constantly transported northward. The intersection of cold and warm air flow is mainly located in the central and eastern regions of China, which creates favorable circulation conditions for large-scale rain and snow weather.

This year's atmospheric circulation anomaly is related to the "La Nina event" that is taking place in the equatorial Middle East Pacific. Li Weijing, deputy director of the National Climate Center, said that from the perspective of climate change, the current low temperature in the equatorial Middle East Pacific is one of the manifestations of the "La Nina" phenomenon. Statistical analysis shows that the meridional dimension of mid-latitude atmospheric circulation may be strengthened in the winter of the year and the spring of the following year when the strong La Nina event occurred, that is, frequent cold air activities may easily lead to low temperature in most parts of northern and eastern China and more precipitation in the north of the Yangtze River.

Why is this year's heavy snow so slow to "recede"? Experts attribute the reason to the stability of atmospheric circulation. Sun Jun said: "It is precisely because of the stable atmospheric circulation during this period that the warm and humid airflow and cold air in the southwest have been around 30 degrees north latitude, especially in the middle and lower reaches of the Yangtze River, so there will be no obvious turning point in the recent rain and snow weather."

It is indeed the result of abnormal atmospheric circulation under La Nina phenomenon. ...

But personally, I think there is a secondary condition. ..

Now, because China is developing rapidly, and the development of China cannot be separated from industry. Industrial emissions of carbon dioxide rank second only to the United States. So in summer, the temperature in China is too high. Even in winter, the sun is still very hot. This leads to a large amount of evaporation of water. Because of the hot weather, a lot of water vapor over the Three Gorges area in China has not dropped sharply, but has been added by new water vapor, so it has been entering. ..

As China is a coastal country, there is a summer monsoon in summer and a winter monsoon in winter ... In summer, it blows from the Australian monsoon region and the Shaway monsoon region on the sea to Siberia on the Asian continent, but in winter, it is just the opposite ... Under the combined action of the winter monsoon and the atmospheric circulation anomaly under La Nina phenomenon, a large amount of water vapor condenses into crystals when moving south. At this time, a lot of water in the south turned into rain and a lot of ice (including snow). ..

A large amount of water storage in the Three Gorges Dam caused a large amount of water vapor to float in the air ... and La Nina phenomenon led to this heavy snow. ....