Behind the weather

The first round of heavy snowfall has hit since winter, behind it? The mastermind? It is the interaction between warm and humid airflow and weak cold air. Because of the westerly belt, the water vapor channel in southwest China is opened, which makes the water vapor transportation smoother. Driven by this strong weather system, the development of low-level jet and surface cyclone is strengthened, and the interaction between warm and humid airflow and weak cold air leads to this round of heavy snowfall. The westerly belt, also known as storm circle and prevailing westerly belt, is one of the planetary wind belts. It is located in the mid-latitude region of the northern and southern hemispheres, between the subtropical high pressure zone and the subtropical low pressure zone, and it is the zone where heated hot air over the equator meets cold air over the polar regions. Next, let's see, heavy snow? The mastermind? .

1. The westerlies bring water vapor and warm air. The westerly belt is located at 35 degrees north latitude in the southern hemisphere and the northern hemisphere. ~65? The air movement in this area is mainly from west to east, especially in the middle and upper troposphere and the lower stratosphere. So most of the areas affected this time are North China and Northeast China, and the snowfall in these two areas will suddenly increase. However, due to the high temperature in the early stage, there will be no catastrophic snowfall, just an ordinary snowfall.

Second, the reason for the formation of westerly belt and the rotation to the earth play a leading role in the direction of air flow. According to the general structure of atmospheric circulation, the mid-latitude airflow is transported to the polar regions. So the two air currents in the southwest will overlap in North China and Northeast China. This airflow carries warm and humid air from the tropics and oceans all the way to the polar regions. Then I met the cold air from the north, so there was rain and snow.

Third, there will be no snowstorm this time. There will be no heavy snowstorm in this snowfall, mainly because the temperature in the northern region has been relatively high since winter and the cold air is extremely weak. The warm and humid airflow will continue to advance. After a short cliff cooling, there will be a new round of warming. Of course, the warm winter we are familiar with will come back.