Four quasi-static stops in China

The four quasi-static stops in China are: Jianghuai quasi-static stop, South China quasi-static stop, Tianshan quasi-static stop and Yunnan-Guizhou quasi-static stop. The cloud system of quasi-static front is mainly divided into two types, and the corresponding weather phenomena are rain and no rain respectively. The quasi-static front is controlled by high pressure, the warm air on the front is dry, the vertical movement is small, and no obvious clouds are formed. The wet and cold air below it rises along the terrain to form stratocumulus clouds, which will bring sporadic precipitation or no precipitation.

First, the quasi-static front of Jianghuai area.

In the Jianghuai Valley of China, warm and humid air from the ocean reaches the banks of the Yangtze River from June to July in early summer every year. At this time, the cold air force controlling the Jianghuai basin is still strong, and it is not easy to retreat to the north quickly. Cold and warm air masses confront each other in the middle and lower reaches of the Yangtze River and Huaihe River Basin, forming a famous weather system-Jianghuai quasi-static front, resulting in continuous rainy "Meiyu" weather.

Second, Kunming quasi-static stop front

Kunming quasi-static front, also known as Yunnan-Guizhou quasi-static front, is located in Yunnan-Guizhou Plateau. The cold air that hits the southwest in winter mainly comes from Mongolia-Siberia. Because of the long distance and the blocking of mountains along the way, the strength is greatly weakened, and the cold air gradually becomes "static", that is, it changes from a cold front to a quasi-static front, which is the famous quasi-static front in Kunming. After entering the winter half year, because the pressure belt and the wind belt moved south, the westerly belt also moved south. Blocked by the Qinghai-Tibet Plateau, the west wind is divided into north and south. The westerly airflow of the northern branch flows to the Pacific Ocean through the northwest, north China, northeast China and east China. The southerly westerly airflow flows eastward along the southern margin of the Qinghai-Tibet Plateau, enters Yunnan through the northern Indian Ocean, forms a southwest warm and humid airflow, rises along a quasi-static front, and forms a cloud system and precipitation over Guizhou.

The front of Kunming quasi-static front is mainly between Yunnan and Guizhou, with a slightly northwest-southeast trend. In winter, most areas of Guizhou are often covered by static fronts. Because it is located on the cold air side, the wind direction is northerly, the temperature is low, and the rain is continuous, so there is a saying that it will clear up in three days. Guiyang is named after "insufficient sunshine is very precious". However, under the control of a single heating mass, the sky in Yunnan is blue, the sun is shining and the temperature is high. Kunming's latitude is low, and the barrier effect of the northern plateau and mountains is obvious, so it is not cold in winter; Because of the high altitude, it is not hot in summer, so the four seasons are like spring, which is called "Spring City".

Thirdly, the quasi-static front in South China.

South China quasi-stationary front refers to the stationary front active in South China, also known as Nanling stationary front. Most of them are caused by the weakening of cold air and the blocking of Nanling mountains after going south, which are distributed in the east-west direction and are important weather systems affecting South China. Mainly in Nanling Mountains or the South China Sea. It can be seen all year round, but it mostly appears in winter and spring, with the least in autumn. The precipitation in winter is not strong, and heavy rain can appear in spring and summer, lasting for several days, even exceeding 10 days. The position of quasi-static front in South China varies with seasons. In the winter half year, the cold high pressure on the north side of the front is powerful, and the front area is located in the south; In the summer half year, the subtropical high on the south side of the front is strong, which makes the front position northward.

Fourthly, the Tianshan quasi-static front.

After the weak cold front from Siberia and the North Atlantic enters the Junggar Basin, it is blocked by Tianshan Mountain, which makes the cold front stagnate and often forms a quasi-static front of Tianshan Mountain with the nature of topographic front, resulting in cloudy or light snow weather. The excessive precipitation in winter and spring in the northern slope of Tianshan Mountain and most parts of northern Xinjiang is related to the quasi-static frontal activity in Tianshan Mountain.