Why does the temperature in the north suddenly drop sharply?

This wave of cold air is divided into three roads, which enter from northwest, south-central Inner Mongolia and northeast respectively. Then these three cold air flows to the central region, and finally directly attacks most parts of our country south. Its influence is that cold air moves southward rapidly, forming a "fast southward movement" mode, such as Guangdong and Fujian. The warmth in Hainan also began to cool sharply at the beginning of this month. On the other hand, the situation in the northern region is more serious. After cold air enters the north, the temperature in the north will drop sharply, generally between10 ~15 ~ 84451a day. Especially in the northwest and northeast of China. Because it is already very cold in the north, the temperature drops sharply after the cold air passes, just like falling into an "ice cave".

Rainfall is the main form in southern China. The combination of rainfall and low temperature means that the wet and cold in the south will be more serious. It may start to snow in the north, especially in Inner Mongolia and Northeast China, and even in the Middle East, Heilongjiang, Jilin and Liaoning in Inner Mongolia. Speaking of this, many friends will worry that the storm in the northeast will once again lead to difficulties in grain transportation.

The subtropical high in the northern hemisphere has a great influence on the climate in summer and autumn in China. Both the summer rainstorm in Henan and the autumn rainstorm in Shanxi are related to the super subtropical high, but the subtropical high will basically retreat from the mainland in winter. Because of the high pressure, air will flow from here to the low pressure area, and the subtropical high pressure area will split into two airflow, one to the south and the other to the north.

The westerly wind will also encounter cold air from the polar regions, which will be forced to rise under high pressure, leading to updraft and forming a low sub-polar pressure zone. The polar vortex and the peripheral westerly belt are trapped in the cold air at high latitudes in the Arctic to some extent, and it is not easy to move southward. When the temperature in the Arctic is low, the pressure difference will be large, and the polar vortex and the western region will be stronger, with a shape close to a circle and a smaller range, which has a strong blocking effect on cold air.

Once the arctic temperature rises, the polar vortex will be relatively weak, irregular in shape, and even split into two parts, one in North America and the other in Siberia. The western region is also often vacillating. The warm peak in the high temperature area in the south may rise northward and push towards the North Pole. Under the attack of the hot peak, the polar vortex containing a lot of cold air was forced to move southward, and the cold air reached China directly, forming a strong cold wave.

As we have said, La Nina is different from El Nino. It will not change the climate, but will increase the intensity of extreme weather. In other words, when La Nina happens, it will make the climate more extreme. For example, it will make cold air activities more frequent and aggravate colds. So from this point of view, this winter may be colder.