What is freezing rain?

Have you ever seen such rain? It was obviously liquid rain when it rained, but it turned into ice as soon as it landed. This is what people often call freezing rain.

Freezing rain usually occurs in winter and early spring. When it comes down from the air, as soon as it touches objects near the ground, such as branches, wires or other objects, it will immediately freeze into a smooth, crystal clear ice shell. Sometimes when it freezes, it will drop water and hang down like an icicle. The ice formed by freezing rain is called "Song Yu" in meteorology, and some people call it "ice".

How is the freezing rain formed? In the cold season, the temperature in the clouds is generally below 0℃, and it should snow, but it is not snow but rain. This is because although the temperature in the cloud is below 0℃, the radius of water droplets in the cloud is too small, the surface is bent badly, or there is a lack of solid substances as freezing nuclei, which can not change the molecular structure of water into ice molecular structure and form supercooled water droplets. When it comes down, it freezes into rain. Although rainstorm rarely happens, it will freeze trees, crush power lines and affect traffic, so it is very important to take precautions.

In the cold winter, sometimes it is neither rain nor snow, but supercooled raindrops or Mao Mao rain around zero. When they fall on the cold objects on the ground, they immediately freeze into a crystal clear layer of ice, which is called freezing rain, commonly known as ice. The thickness of freezing rain can generally reach 10 ~ 20mm, and the thickest is 30 ~ 40 mm. When freezing rain happens, the wind is often strong, so freezing rain has a great influence on transportation, especially communication and transmission lines. According to meteorologists, freezing rain is a precipitation phenomenon under a specific weather background. During this period, the northwest airflow and southwest airflow over the Jianghuai Basin are very strong, cold air invades the ground, and warm air flows northward over1500-3000m. The vertical structure of the atmosphere is cold from top to bottom and warm in the middle, with ice crystal layer, warm layer and cold layer from top to bottom. That is to say, the atmospheric temperature above 3oo meters is often below-10℃, at an altitude of about 2000 meters, the atmospheric temperature is generally around 0℃, while the temperature below 2000 meters is below 0℃. Freezing rain mostly occurs from the first ten days of 1 month to the first ten days of February, and lasts for more than 1 month, with the characteristics of early in the north and late in the south, early in the mountains and late in the plains, but the end is the opposite. In mountainous areas with higher terrain, freezing rain starts early and ends late, and the freezing rain period is slightly longer. For example, in Guangmingding, Huangshan Mountain in southern Anhui, the freezing rain usually starts from the first ten days of 165438+ 10 and ends in the first ten days of April of the following year, lasting for five months. According to statistics, the freezing rain weather in the Jianghuai basin occurs once every 2-3 years along the Huaihe River and once every 7-8 years south of the Huaihe River. However, in mountainous areas, there is a big difference between valleys and mountain tops. There is almost no freezing rain in some valleys in mountainous areas, while there is freezing rain in higher mountainous areas almost every year.