Affected by the eastward movement of the westerly trough, there will be snowfall in Inner Mongolia, North China and Northeast China. What is a westerly trough?

The westerly trough is an air convection phenomenon.

The westerly trough generally runs from northeast to southwest, and its formation is generally as follows: the warm and humid airflow in southwest moves upward, the cold and dry airflow in northeast sinks downward, and the pressure difference is formed when it rises and falls. The high pressure side is a ridge and the low pressure side is a groove. And the trend of this pressure is to move southwest, so it is called? West wind trough? . Because the temperature in the northeast part of the westerly trough is low and the air pressure is high, the temperature in the southwest part is high and the air pressure is low, which creates three unique climate phenomena of the westerly trough, which will be explained in detail below.

1. Rain in the northeast and southwest: Because the southwest of the westerly trough is warm and humid, as the westerly trough moves to the southwest, the water vapor contained in it will condense and nucleate with the movement, resulting in rain or snowfall. The northeast of the westerly trough is cold and dry, so the weather is generally sunny, with no rain or snowfall. Take this example, the snowfall in Inner Mongolia, North China and Northeast China is the phenomenon of water vapor condensation when the westerly trough moves.

2. The westerly trough is divided into long-wave trough and short-wave trough: the short-wave trough moves faster and the long-wave trough moves slower. Because the short-wave trough moves quickly, the weather changes dramatically, and there is often light snow or heavy snow, so the climate change of the long-wave trough is mild. The long wave trough moves slowly, and the weather changes little, even sometimes it doesn't rain or snow, but the temperature changes little. The westerly trough in this example is a long wave trough.

3. The Qinghai-Tibet Plateau also has this phenomenon, which is called Northwest Trough. The formation principle of Northwest Trough is the same as that of Genxi Wind Trough, and its essence is air convection. The difference between the northwest trough and the west trough is mainly the different areas of influence. The areas affected by the Northwest Trough are Shaanxi, Gansu and northern Sichuan. The westerly trough is introduced in all aspects above, and the northwest trough is also listed as a comparison. The westerly trough is just a normal climate phenomenon, so we can take precautions.