Freezing rain is composed of supercooled water droplets. When it encounters an object with a temperature below zero degrees Celsius during landing, it will quickly freeze into ice. Let me introduce the related knowledge of freezing rain in detail for you.

Form an environment

In winter, rain falls on trees, tall buildings, rocks, telephone poles and other objects and immediately becomes ice. People used to call it "dripping into ice". This kind of rain is called "freezing rain" in meteorology, and its condensate is called "Song Yu". It is different from ordinary water droplets, but a kind of supercooled water droplets with a temperature below 0℃. In the cloud, it should be condensed into ice particles or snowflakes, but it can't find the necessary freezing core when it freezes, so it becomes a drop of supercooled water, which can freeze when it touches an object.

Fall on wires, branches, and the ground, and then form a thin layer of smooth ice. The ice is getting thicker and thicker, and it freezes while flowing in the process of condensation. As a result, a series of stalactite-like icicles and ice thorns, commonly known as "ice hanging", have emerged. They are crystal clear, and when they meet the sun, they give off colorful light, which is really beautiful! Unfortunately, when its weight exceeds the carrying capacity of the object, tragedy happens.

To form "freezing rain", it is often inseparable from specific weather conditions to make supercooled water droplets land on the ground smoothly: the temperature of the air layer about 2000 meters near the ground is slightly lower than 0℃; The temperature of the air layer from 2000 meters to 4000 meters is higher than 0℃, which is warmer; The upper layer is lower than 0℃, so the supercooled water droplets, ice crystals and snowflakes on the upper layer of the cloud fall into the warmer gas layer and become liquid water droplets. Then it falls and enters the frozen layer which is not too thick. When they fall with the wind and are ready to freeze, they have already touched the cold objects in the form of supercooling, and suddenly formed a solid "freezing rain"! [2]

Formation process

Freezing rain is composed of supercooled water droplets, which collide with objects with a temperature below 0℃ and freeze immediately. Raindrops below 0℃ can remain supercooled in air with a temperature slightly lower than 0℃, and their appearance is the same as that of ordinary raindrops. When they fall on an object with a temperature below 0℃, they will immediately freeze into a smooth and transparent ice layer, which is called snowball. Severe snowstorms will crush trees and telephone poles, stop communication and power supply, hinder road and railway traffic, and threaten the flight safety of aircraft.

After the sun came out, the icicles in the sun shone, enchanting and charming, and the freezing rain added beautiful and moving scenery to people. But the harm it causes is also very serious. For example, the weight of the conductor increases after freezing, and it will shrink when it is cold, which will lead to the fracture of the conductor and the interruption of communication and transmission. Crops are frostbitten and frozen to death after freezing rain; If the ground freezes, traffic accidents will increase sharply. Therefore, the freezing rain for several days in a row has caused great disasters.

The harm of freezing rain

The scenery of freezing rain is worth seeing, but after all, it is disastrous weather, and the harm caused cannot be ignored. [3] Highway traffic is blocked by ground icing, and traffic accidents increase accordingly. If the ground freezes, it will freeze the green winter wheat or the crops planted in early spring. In addition, freezing rain will also destroy young forests and frostbitten fruit trees in a large area. The thickness of freezing rain can generally reach 10 ~ 20mm, and [4] the maximum thickness 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. 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, freezing rain generally starts in early October of 165438+ and ends in early April of the following year, lasting for five months. According to statistics, the freezing rain weather in the Jianghuai basin [5] 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. Freezing rain is a disastrous weather, and a large amount of freezing will break power lines and telephone lines. Severe freezing rain will cause houses to collapse. When an airplane flies in a cloud with supercooled water droplets, water will accumulate in the wings and propellers, which will affect the aerodynamic efficiency of the airplane and cause a crash.

Highway traffic was blocked by ground icing? Traffic accidents have also increased. If the fields freeze, winter wheat will freeze to death, or crop seedlings or young forests and fruit trees planted in early spring will freeze to death. Will the power cord and telephone line be crushed after freezing rain accumulates? Interrupt telecommunications and transmission. Even severe freezing rain will cause houses to collapse. When the plane flies in the clouds with supercooled water droplets, the wings and propellers will accumulate water. It affects the aerodynamic efficiency of the aircraft and leads to the crash.

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Characteristics of freezing rain

Climatic characteristics

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.

Time characteristics

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.

Regional characteristics

Freezing rain is more common in mountainous areas and lake areas; There are many in the south and few in the north of China; There are many wet areas and few dry areas; There are more mountains than plains, and there are the most mountains. 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.

The area with more freezing rain is Guizhou Province, followed by Hunan, Jiangxi, Hubei, Henan, Anhui and Jiangsu, as well as Shandong, Hebei, Shaanxi, Gansu and southern Liaoning. There will also be freezing rain in northern Xinjiang and Tianshan area, central Inner Mongolia and eastern Daxinganling. Guizhou is the province with the most freezing rain in China, and it is most prone to freezing rain from 65438+February to February of the following year. Weining, Guizhou is known as the "hometown of freezing rain", and the number of freezing rain days in Weining can reach 44.6 days. Among them,1October is the most, with an average of 16.8 days, and the whole year is 65438+ February/kloc-0.1day.