What are concentrated rime and rime?

Rime, commonly known as "hanging trees", is very common in the north. It is a natural phenomenon similar to the first frost that can be seen in northern winter, and it is a kind of snow and ice beauty. Rime is the result of countless unfrozen droplets below 0℃ in fog piled up with the wind and frozen on branches and other objects, showing as white opaque granular structure deposits.

Beautiful scenery of snow and ice

When supercooled water droplets (temperature below 0℃) collide with objects with the same freezing temperature, rime will be formed. When water droplets are very small and freeze as soon as they touch objects, a rime layer or rime deposit will be formed. The rime layer is composed of small ice particles with pores between them, which leads to a typical white appearance and granular structure. Due to the rapid freezing of each supercooled water droplet, the cohesion between adjacent ice particles is poor and it is easy to fall off from the attachment. Rime is also most likely to form at the top of the mountain surrounded by Leng Yun. In cold weather, steam fog near springs, rivers, lakes or ponds can also form rime.

There are two kinds of rime. (1) supercooled water droplets quickly freeze into small particles of ice, which is called particle rime, and its structure is relatively compact. (2) The crystal rime formed by the condensation of supercooled droplets is loose in structure, and it will fall off with slight vibration.

Jilin Rime in China, with its beautiful appearance and unique charm, has been praised by an endless stream of Chinese and foreign tourists. Whenever rime comes, it is like a strong wind in spring. At night, it blows open the petals of ten thousand pear trees. On the ten-mile-long bank of Songhua River in Jilin City, willow trees are full of silver flowers and pine trees are full of silver chrysanthemums, which brings people into a picturesque fairyland. Rime occasionally appears in some places in the north. Rime in Jilin is not only loose in structure and low in density, but also harmless to human body, and has many benefits.

The decline of air quality in modern cities is a worrying problem, and Jilin rime can become a natural cleaner of air. When people watch rime in Jilin, they will feel that the air is particularly fresh, relaxed and free, nourishing their hearts, just like a flower in Yushu. This is because rime has the innate function of purifying air. There are a lot of invisible particles in the air, most of which are below 2.5 microns in diameter, which is equivalent to 1/40 of the diameter of human hair. They are very small, very light and suspended in the air, which is harmful to people's health. According to the survey and test of particulate pollution hazards in the United States, the death rate of cities with heavy particulate pollution is higher than that of cities with light particulate pollution 15%, and particulate matter causes 50,000 deaths every year, most of which are elderly people and children who have already suffered from respiratory diseases. In the early stage of rime, particles were adsorbed and settled on the earth to purify the air. Therefore, Jilin rime is not only flawless in appearance, but also a natural large-scale air purifier.

Rime is a kind of natural beauty that people generally appreciate, but it sometimes becomes a natural disaster. Severe rime sometimes breaks wires and trees, causing great losses.

The formation mechanism of rime is similar to that of rime, which generally appears on cloudy days, mostly caused by cold rain, lasts for a long time, has little daily variation, and can be produced day and night.

Rime is a precipitation phenomenon under a specific weather background. The typical weather of rime formation is mild cold (0 ~ 3℃), with rain, strong wind and large fog drops, which usually occurs when cold air meets warm air, which is very powerful. For example, in China, during this period, the northwest airflow and southwest airflow over the Jianghuai Basin were very strong, and cold air invaded the ground. At this time, the bottom air temperature is low (slightly lower than 0℃), and the warm air with a temperature higher than 0℃ flows northward1500 ~ 3000m, forming a warm air layer or clouds, and the upper atmosphere with a temperature lower than 0℃ is above 3000m. The temperature of clouds is often below-10℃, that is, at a height of about 2000 meters, the atmospheric temperature is generally around 0℃, while the temperature below 2000 meters is below 0℃, that is, there is an inversion layer near the ground. 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.

Snowflakes falling from the ice crystal layer melt into raindrops when passing through the warm layer, and then enter the cold air layer near the ground, and the raindrops quickly cool down and become supercooled raindrops [there is a physical property in the atmosphere that they are still in liquid state when the temperature is tens of degrees below zero (℃), which is called "supercooled" water drops, such as supercooled raindrops and supercooled fog drops]. The fog droplets and water droplets that form rime are large and the condensation speed is fast. Because the diameter of these raindrops is very small, although the temperature drops below 0℃, they fall before freezing.

When these supercooled raindrops fall to the ground with branches, wires and other objects at a temperature below 0℃, they gather and spread on the surface of the objects, and immediately freeze into a transparent or translucent ice layer like frosted glass, making branches or wires become thick popsicles, which are usually smooth or slightly raised in appearance, and sometimes drop and freeze, forming long icicles and becoming what we call "rain songs".

Rain stops are more common in mountainous areas and lake areas. In most parts of China, the rainy season occurred from February 65438 to March the following year. The distribution characteristics of the annual average number of rime days in China are more in the south and less in the north (however, due to the warm winter, the low temperature near 0℃ rarely occurs in South China, so there is neither hail nor rime); There are many wet areas and few dry areas (especially in mountainous areas). Almost all the stations with an average rainy day of 20 ~ 30 days in China are alpine stations, while the average rainy day of most substations in plain areas is less than 5 days.

The ice flower world composed of rainbows is embedded into the vegetation bit by bit, forming all kinds of beautiful ice flowers, while others form stalactite-like ice hangings, and the mountains are all covered with silver. The vast mountains and peaks are icebergs, and the pine trees and shrubs with strange flowers and plants everywhere have become Yushu in full bloom, like silver branches and jade leaves, which is particularly attractive; The ice covered with branches and trees is like a bead curtain hanging down, and the mountain wind is swaying, which is particularly dazzling, such as entering the glass world; The ice is jingling, just like Yue Xian, melodious and harmonious, crisp and pleasant; On the rocks, it is a vast expanse of snow, like snow, as if covered with a layer of glittering jade clothes, radiant. In the bright sunshine in winter, it is especially glittering and translucent, which is a spectacle.

A world of ice flowers composed of rainbows.

Although rime makes the earth white and crystal clear, it is a disastrous weather, which is difficult to eradicate and extremely destructive. The harm it causes cannot be ignored.

There is a clear difference between rime and surface water icing. Rime freezes in the process of falling, which can immediately attach to the exposed surface of the object without loss, forming an increasingly thick solid ice layer, thus increasing the load of the object. Severe rime will break branches, crops and power lines, crush houses and hinder traffic.

The biggest harm of rime is to interrupt the power supply line. In snowy days, the high-voltage tower can bear 2 ~ 3 times the weight; But if it rains, it may bear 10 ~ 20 times the weight of the wire. When there is rain on the wires or branches, when the wires freeze, they contract when they are cold. Coupled with the vibration brought by the wind and the influence of the weight of rain, electric wires and telephone lines can be overwhelmed and crushed, and telephone poles from several kilometers to dozens of kilometers will fall in rows, causing power transmission and communication interruption, seriously affecting local industrial and agricultural production. In many cities in history, high-voltage lines collapsed in rows because of rain.

Rime will also threaten the flight safety of aircraft. When an airplane flies in a cloud with supercooled water droplets, the wings and propellers will accumulate water, which will affect the aerodynamic performance of the airplane and cause a crash. Therefore, in order to fly safely in winter, modern aircraft are basically equipped with deicing equipment. When there is snow on the road surface, road traffic is blocked by the ground icing, and traffic accidents increase accordingly. The ice on mountain roads is also very dangerous, which often makes cars slide to cliffs.

Because the ice is constantly frozen and thickened, branches are often broken, so snow can also cause serious damage to trees. Hard ice will also erode the crops covered under it. If the wheat field freezes, it will freeze the green winter wheat or the crop seedlings planted in early spring. In addition, rime can also destroy young forests and frostbitten fruit trees in a large area. Agriculture, animal husbandry, transportation and other aspects have suffered huge losses. Severe freezing rain will also cause houses to collapse, endangering people's lives and property.

The possibility and degree of disasters caused by rime is much higher than that caused by rime. In high latitudes, rime is a common disastrous weather phenomenon. The main methods to eliminate the rime disaster are to take artificial ice falling measures when the rime appears, to mobilize residents along the transmission lines to continuously scrape the rime on the power lines, and to take support measures for trees and power grids; Installing deicing equipment on the plane or simply flying around the freezing rain area can partially alleviate the harm caused by rain.

In a word, snowstorm is a low temperature disaster in winter. In order to travel safely, aviation, railways, highways, electric power, telecommunications, postal services and other departments and the general public should attach great importance to it.