The influence of cold wave weather on China

The cold wave is a large-scale cold air activity, so when the cold wave strikes, the weather changes dramatically. However, due to the different seasons, geographical conditions and cold wave intensity, the weather changes in different places are also different. Generally speaking, the most prominent thing in winter is that the temperature drops and the wind direction changes dramatically when the cold front passes through. There is often a strong northerly wind behind the front, sandstorms in northwest and Inner Mongolia, and occasional snowfall north of Huaihe River. As soon as the cold front passed the weather, the eyes lit up. After the cold front crosses the Huaihe River, the precipitation opportunities increase, especially when the cold front is slow or static in the south of the Yangtze River, the precipitation time will last for a long time.

Cold wave weather has the greatest impact on agriculture. The temperature drop caused by cold wave can reach 10℃ or even above 20℃, which usually exceeds the cold tolerance of crops and causes freezing damage to crops.

The physiological temperature of cold tolerance of different crops in different regions also has certain limits. For example, spring wheat, beans and oil crops in the north are all cold-tolerant crops, which can tolerate the low temperature of -7 ~- 10℃, radish can tolerate the low temperature of -6℃, Chinese cabbage can tolerate the low temperature of -4℃, and corn and potato can only tolerate the low temperature of -3 ~-2℃. Moreover, the cold tolerance of various plants at different growth and development stages is also different. For most plants, when the temperature drops to about 0℃, it will obviously suffer. Almost every cold wave in history will cause large-scale disasters to crops, and the degree of disasters will vary greatly due to the different invasion areas of cold air.

After the cold wave crosses the border, the temperature drops sharply, and the cooling can last for one to several days. The temperature drop in northwest and north China is large, and that in central and south China is small, but freezing frost may occur. For example, in 1955 and 1 two months, the extreme minimum temperature of-14.6℃ appeared in Wuhan,-19.2℃ appeared in Shanghai and -2. 1℃ appeared in Nanning. Among them, many areas in Jiangsu, Anhui, Hubei, Hunan, Jiangxi and other provinces experienced 10- 15 days of continuous heavy snow and freezing rain, which blocked traffic and telecommunications and caused heavy losses in agricultural and animal husbandry production. In spring and autumn, in addition to strong winds and cooling in the south of the Yangtze River basin, there are often rain and snow in cold wave weather. Sometimes there will be severe weather such as thunderstorm and hail, especially the frost caused by the last frost, the first frost and the cold wave, which is more threatening to crops in North China and Central China and often leads to serious production reduction.

Cold wave and strong cold air usually bring strong wind, cooling, freezing rain and snow, which is the main disastrous weather in winter half a year in China.

Strong winds can derail trains and even overturn them. Trains overturned by strong winds in China have occurred in many places in Xinjiang. The Lanzhou-Xinjiang Railway will pass through the "Bailifeng District" near Hami and the "Lisanfeng District" in Dabancheng, Tianshan Mountain. From 196 1 to 1982, strong winds overturned trains as many as 10 times. In windy seasons, trains often fail to run on time.

Strong winds also have a significant impact on civil aviation. Wherever cold air goes, the average wind speed is generally above 15m/s, and the gust is above 25m/s, and it lasts for a long time. Strong winds make it easy for aircraft to take off and land, such as tire breakage and landing gear fracture.

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.

The cold wave will not only lead to strong winds and cool weather, but also lead to rain and snow at the intersection of cold and warm air, which will have a great impact on roads, railways and people's travel. In addition, the cooling brought by the arrival of the cold wave will reduce the temperature, which is not conducive to the melting of snow, and some areas will still freeze, which will have an adverse impact on transportation. If the cold wave lasts for a long time, it will further increase the icing thickness of the road, leading to the forced closure of expressway and the increase in the number of stranded passengers; This will further increase the transportation pressure of the railway. The thickness of road icing may increase more traffic accidents and bring more safety hazards. If the damage to the power grid is further aggravated, it may endanger the railway power grid again, thus affecting the normal operation of trains. Continued freezing weather will lead to flight delays again.