The Big Jump World Cup is about to start, Shougang's "Snow Flying Sky" starts making snow! Why use "ice-like snow"?

The 2023/2024 FIS Snowboard and Freestyle Skiing Big Air World Cup, hosted by the FIS and co-organized by the Chinese Ski Association, Beijing Sports Bureau and the People's Government of Shijingshan District, Beijing, will be held from November 30 to December 2 at the Shougang Ski Big Jump - "Xue Feitian".

On November 17, the snowmaking work of the Shougang Ski Big Jump was officially launched. The snowmaking work will last until November 27. After the snowmaking work is completed, the athletes will conduct pre-match training.

(Photo source: Beijing Evening News)

Snow quality is an important guarantee for the ski jumping event. Since this year's event is held earlier than in previous years and the weather temperature is higher, the issue of snowmaking has attracted everyone's attention.

In fact, such concerns are obviously unnecessary. The development of snowmaking technology is enough to enable our country to achieve "free use of snow".

Artificial snow is safer and more controllable

Taking into account the uncertainty of natural weather processes, especially snowfall, international snow sports events generally use artificial snowmaking to pave the snow tracks. The reason is that, on the one hand, artificial snowmaking technology is controllable and does not need to rely on the weather; on the other hand, the threshold of this technology is relatively low - as long as the temperature is below 0℃, the snowmaking machine can work.

"Usually, artificial snowmaking uses 'snow cannon' type snowmaking machines. There are two principles for this type of machine. One is to use an ice-making device to produce very small 'ice flakes', which are then used as raw materials to make snow. The other is the traditional method of mixing high-pressure water and air to make snow," said Su Zhengjun, senior engineer at the China Meteorological Administration's Weather Modification Center.

Traditional artificial snow is made by injecting water into a special nozzle or spray gun, which uses high-pressure air to divide the water flow into tiny particles. When these water droplets encounter the cold outside air, they will quickly solidify into ice crystals before hitting the ground, becoming the snowflakes we are familiar with.

"Artificial snow takes a short time to form, grows quickly, and the shapes of the snowflakes are basically the same. Natural snowfall will have a more obvious change in hardness on the second day," explained Su Zhengjun.

In the early morning, when the outdoor temperature is low, the natural snow is usually more solidified and hard, similar to "ice chips". Although this state of snow allows skiers to reach a faster sliding speed, it also makes the snowboard's grip less effective. Especially for novices, if the soft natural snow is not compacted, the snowboard is very easy to sink into the snow, causing accidents such as rollover and sudden stop.

The smooth machine-groomed snow track is also called "noodle snow" by enthusiasts, and skiing on the machine-groomed snow track is likened to "eating noodles." The picture shows the machine-groomed snow track in Changbai Mountain International Resort, Jilin (Photo source: Xinhua News Agency)

Creating a "rubber track" on snow

It is easy to understand that artificial snow can help us get rid of our dependence on natural snowfall. So why do some winter sports tracks still use artificial snow in areas where there is snow all year round and the snowfall is extremely abundant?

This brings us to another advantage of artificial snowmaking: it is customizable. According to the needs of different events and venues, artificial snow can freely adjust the particle size, water content and hardness of the snowflakes.

For example, alpine skiing, a traditional event of the Winter Olympics, has always been hailed as the "crown jewel of the Winter Olympics" because of its high viewing value. However, the participants in this event move at very high speeds (up to 248 kilometers per hour) and are very dangerous, so the requirements for the track are more stringent. In order to build a snow track that meets the international standards for alpine skiing, the snow used is not ordinary natural snow, but artificial "ice-like snow".

The so-called ice-like snow is used to describe the state of snow quality on the ski resort. In this state, the density of snowflakes is about 0.65 grams per cubic centimeter, and the surface of the ski slope remains crystalline, as if there is a thin layer of "ice shell", similar to the ice surface. Such a ski slope is hard and not easy to be damaged. When athletes turn at high speed, the surface of the ski slope can be guaranteed not to deform. No matter which athlete comes out, the state of the ski slope is relatively perfect.

Competition-level snow trails are denser and more solid, so you can slide faster, but it also hurts more if you fall (Image source: WeChat official account of "Chai Zhidao")

If ice-like snow is used to pave the track for alpine skiing, it is like building a "plastic track" on the snow. It can not only reduce the friction of the track surface on the skis and significantly improve the athletes' performance, but also improve the athletes' comfort when skiing, protect their body joints, and extend the athletes' professional sports careers as much as possible.

Shougang Ski Jump uses crushed ice to make snow

The snowmaking method this time is to crush ice. Ice crushers are used to crush ice cubes into snow powder, and snowplows push and compact the snow powder, which is then piled up from the bottom of the big jump platform to the top, covering the snow track. After the track is laid, water and salt will be sprayed on the snow surface to form the final "ice-like snow", ensuring that the snow conditions for each athlete are basically the same when sliding.

Snow quality is an important guarantee for the ski jumping event. "Ice-like snow" can not only improve athletes' performance and skiing comfort, but also protect athletes' bodies. The snowmaking team for this event has many years of experience and has served large-scale events such as the Winter Olympics. The team will also communicate with athletes about snow quality to meet their needs.

Unlike other temporary venues, the Shougang Ski Big Jump, as the world's first permanently preserved and used big jump competition venue, can meet the load-bearing requirements of snowgrooming vehicles during track construction, which also sets a precedent for using snowgrooming vehicles to pave big jump ski tracks.

(Photo source: Beijing Evening News)

Snow conservation and storage technologies ensure track quality

In fact, for a long time, creating high-quality ice-like snow tracks has been a "bottleneck" technical difficulty in my country's ice and snow industry. In order to welcome the Beijing Winter Olympics and Paralympics, scientific researchers have established the territorial parameters for making ice-like snow in the Beijing Yanqing and Zhangjiakou competition areas through unremitting efforts. At the same time, with the help of a set of snow-making processes such as water injection and compaction, they finally successfully made qualified ice-like snow that meets the climatic conditions of the continental monsoon area. The natural snowfall in the local mountainous areas in winter has become the "landscape snow" that decorates the Winter Olympics competition area.

In fact, for the high-standard Winter Olympic track, natural snowfall is a "burden". If it snows, the soft natural snow will make the "smooth as a mirror" ice-like snow track fall short. In addition, since the Beijing Winter Olympics and Paralympics are in the transition period between winter and spring, they may encounter other extreme weather, such as sudden rainfall, which will cause thin ice to form on the surface of the track, increasing the risks faced by athletes during the competition.

On February 23, 2021, staff at the National Alpine Skiing Center ("Xue Feiyan") in Yanqing were inspecting and repairing the track (Photo source: Xinhua News Agency)

According to the planning of scientific researchers, if the weather is really bad, the staff will immediately use the snow groomer to re-compact the snow track and perform emergency finishing on the track. At the same time, in order to ensure the quality of the track, they will also use automatic measuring instruments such as ice and snow hardness testers and ice and snow particle size testers for quick testing, so as to ensure that the snow quality is qualified and resume the normal progress of the competition in the shortest time.

It is reported that in order to ensure sufficient snow during the event, the 2022 Beijing Winter Olympics has also made bold attempts in snow storage: taking advantage of the lower temperatures in winter, qualified snow is made in advance, and then the snow is stored in a flat area until it is used the following year.

This seemingly fantastic plan had already passed the feasibility test as early as 2017. The Beijing Winter Olympics Organizing Committee successfully carried out a snow storage test at the Yanqing Shijinglong Ski Resort. After the test in the spring and summer of the following year, more than 60% of the artificial snow was successfully stored.

Source: Beijing Science and Technology News, some content compiled from Beijing Evening News

Written by reporter Wang Xueying

Editor/Ding Lin

Interviewed expert: Su Zhengjun (Senior Engineer, Weather Modification Center, China Meteorological Administration)