Blizzard is online! Why do we need artificial snow?

It’s snowing again!

The previous snow has not yet melted, and a new heavy snow has quietly drifted into Beijing. When I left for work in the morning, granular snowflakes were already falling, and by the morning, they had turned into heavy snow. I wonder if my friends' commute to work today was affected by the snowfall? (It doesn't matter if you don't see snow on the way to work, the heavy snow on the way home from get off work has a greater impact!)

At noon, it was still snowing heavily at the Beijing Science Center

Source丨Editor

At 22:00 on December 12, the Municipal Meteorological Observatory upgraded and issued an orange warning signal for heavy snow. It is expected that from the morning of December 13 to the morning of December 15, the city will experience heavy snow to heavy snow, of which 10:00 to 20:00 on December 13 will be the heaviest period of this snowfall process. The snowfall in some areas of Yanqing, Changping, Mentougou, Fangshan, Huairou, Haidian, Shijingshan, Fengtai, Dongcheng, Xicheng, Chaoyang, Daxing, and Tongzhou will reach more than 10 mm. In response to the extreme weather of heavy snow, the Municipal Emergency Management Bureau issued seven warning response measures , and the Municipal Education Commission also issued a notice for students in primary and secondary schools and kindergartens in the city to study at home.

Source: Weibo/Capital Education

The two sudden heavy snowfalls have caused considerable trouble to our friends in Beijing and Hebei. So why did Beijing, which rarely snowed in previous years, suddenly experience a snowstorm this time?

Where did this blizzard come from?

Snowfall is inseparable from cooling and water vapor. On December 10, cold air continued to move southward, while warm and humid air strengthened and moved northward. The combination of the two will trigger a large-scale rain and snow weather, which led to the blizzard. The Central Meteorological Observatory continued to issue a yellow cold wave warning at 6:00 today: From the 13th to the 16th, a strong cold wave will start from Xinjiang and affect my country from west to east and from north to south.

Source: Weibo/Beijing Weather

Not only that, on the 11th, artificial snowmaking operations were carried out in many places in Hebei Province. As of 10:00 on the 11th, the Hebei Provincial Meteorological Bureau organized three aircraft snowmaking operations in the central and southern Hebei and eastern Hebei regions, flying for 12 hours and 16 minutes, burning 79 aircraft smoke strips. The meteorological departments across the province carried out 85 ground artificial snowmaking operations, launched 251 rockets, and burned 166 ground-based silver iodide smoke strips. At the same time, relevant departments in Hebei and Beijing Human Shadow Aircraft carried out three flight operations in Zhangjiakou, Baoding and other places.

After the snow, the roads are slippery and muddy, so why do we need to make snow artificially? In fact, although snowfall in urban areas causes some trouble to everyone, snowfall can effectively improve air quality, help winter wheat survive the winter, and relieve the pressure of forest and grassland fire prevention. Therefore, artificial snowmaking also has its positive significance.

There are two conditions that must be met for water vapor in the sky to turn into rain or snow. One is that there must be a certain level of water vapor saturation (mainly related to temperature), and the other is that there must be condensation nuclei .

Therefore, artificial snowmaking first requires clouds in the sky . Without clouds, it is like a good cook cannot cook without rice. Clouds that can snow are "cold clouds" with a temperature below 0℃. In cold clouds, there are small water droplets condensed from water vapor and small snow crystals condensed from water vapor. But they are very small and light. If there are no conditions for them to continue to grow, they can only float in the air like smoke and dust, and it is difficult for them to fall down.

Rain (snow) rocket launcher Source: China Meteorological Administration

The principle of artificial snowmaking is to spread catalysts into clouds through tools such as airplanes, rockets, and anti-aircraft guns to promote the conversion of cloud water into precipitation and improve the conversion efficiency . For example, spreading silver iodide catalysts to form a large number of artificial ice crystals is equivalent to increasing the condensation nuclei in the clouds, promoting the crystallization of supercooled water in the clouds, and making the small ice crystals in the clouds grow quickly to the point where they can overcome the buoyancy of the air and fall down to form snowfall. This is the credit of artificial snowmaking.

Generally speaking, the effect of artificial snowmaking is quite obvious. When the conditions are right, the amount of snow increased in the affected area can generally reach 15% to 20%, and sometimes even more.

What should you pay attention to when traveling on snowy days?

There is already a lot of snow on the road, and the road is slippery after the snow, which greatly increases the possibility of falling . Most people may get up and pat their buttocks after falling, but for some people, especially the elderly, a fall is likely to cause fractures or even more serious problems.

Source: A short video platform

According to Beijing Youth Daily, on December 11, the proportion of patients injured after falling in the snow at Beijing Jishuitan Hospital increased significantly. As of 17:00, a total of 116 patients were treated in the three hospital areas. Therefore, everyone must be careful to prevent slipping when going out and try to reduce travel.

Once you fall, do not stand up immediately, provided that the environment is safe. You can slowly feel the degree of limb movement. If you feel severe pain, you should call for help nearby. In serious cases, please seek medical attention in time to avoid secondary injuries caused by improper activities. Do not blindly massage the injured part to avoid aggravating the injury. If the injured part is swollen, in severe pain, or obviously deformed, call 120 in time to transfer to the hospital for further treatment.

In the early morning of December 13, the Beijing Emergency Management Bureau issued seven early warning response measures:

1. Citizens are requested to keep warm, prevent cold and frostbite, pay attention to the safety of fire, electricity and gas, and prevent carbon monoxide poisoning.

2. Encourage citizens to reduce travel, and try to take public transportation and subway when traveling; reduce driving, maintain a safe distance and slow down when driving; ride less or no bicycles and electric bicycles.

3. Citizens are requested to avoid visiting mountainous areas and not to enter the mountains unless necessary; take anti-slip measures when driving in mountainous areas; stay away from old trees, structures, walls, plaques and dangerous areas with snow to avoid being crushed; when passing under bridges and eaves, prevent icicles from melting and falling off and injuring people.

4. Primary and secondary schools and kindergartens will implement home-based learning and carry out online teaching activities, allowing learning to continue even if classes are suspended; it is encouraged that employees of enterprises and institutions stagger their get off work hours and work flexibly.

5. All units should pay close attention to weather changes, arrange production and operation activities reasonably, and avoid outdoor operations and outdoor gathering activities unless necessary to ensure the normal operation of the city.

6. Urban operation guarantee units should make every effort to clear snow and ice, provide heating service guarantee, strengthen traffic organization and guidance, pre-position emergency rescue forces, deal with emergencies in a timely manner, and ensure the safe operation of urban lifelines such as water, electricity, gas, and heat.

7. Closely monitor and promptly remove snow from school gymnasiums and other venues, large-span buildings, agricultural greenhouses, temporary structures, and tops of dangerous buildings to prevent collapse. Mountain scenic spots will suspend operations, and large outdoor recreational facilities in non-mountainous scenic spots will suspend operations.

At the same time, in order to effectively deal with ice and snow weather, ensure the safety of vehicles and pedestrians after snowfall, and ensure that the roads are clean and tidy, the Office of the Capital City Environmental Construction Management Committee, the Office of the Capital Spiritual Civilization Construction Committee, and the Beijing Patriotic Health Campaign Committee Office have issued a letter of appeal to all social units and all citizens, calling on all citizens to participate in voluntary snow and ice clearing. If you have spare energy after get off work or school, you can also participate in the snow clearing work in your own community, but please be sure to pay attention to safety~

What safety issues should we pay attention to during blizzard weather? Please see the picture below↓↓↓

This article is compiled from the public accounts: Science Popularization China, People's Daily Science Popularization, CCTV News Client, Central Meteorological Observatory, China Weather Network, China Meteorological Administration, Harbin Meteorological, Ministry of Emergency Management, Beijing Evening News, Hebei Youth Daily, Taiyuan University of Science and Technology School of Chemical Engineering and Technology, etc.