Light snow today | How does “Snow Lady” make snow?

In traditional Chinese culture, there are many gods related to weather, such as Fengbo, Yushi, Leishen, Dianmu, etc. So, is there a god related to snow? During the Xiaoxue solar term, we will talk about how snow is formed based on the legend of our country's snow god.

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01 China’s Snow God

There is a snow god, a deity in ancient Chinese mythology and legends who is mainly responsible for controlling snowfall.

Teng Liu: "Teng" comes from a small vassal state in the east of the Zhou Dynasty - Teng State, and "Liu" comes from the hexagonal feature of snowflakes. The combination of Teng Wengong, the king of Teng State in the Spring and Autumn Period , and "Liu" formed the image of the snow god Teng Liu. Teng Liu as the image of the snow god first appeared in Tang Dynasty literature and was widely used in literary works after the Song Dynasty.

Qingnv (Qingxiao Yuu): Also known as Shuang'e, she comes out in the ninth month of the lunar calendar to spread frost and snow.

In addition to the two snow gods mentioned above, there are also the goddess Gushe, Dong Shuangcheng, Zhou Qiongji, etc., who are also regarded as snow gods in some legends. Their images and stories are relatively scattered and not as widely circulated as Teng Liu and Qingnv.

Among the people in southern my country, there is a legend about a "Snow Granny", who is widely loved and praised.

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02The Legend of Snow Granny

In the folk belief of the Jiangnan region in the old days, the 25th day of the 10th lunar month was considered the birthday of Snow Granny, and also the day when she "brews snow". The weather conditions on this day, such as whether it rains or blows, are used to predict the temperature, amount of rain and snow in winter. If there is a strong wind on this day, it may indicate frequent northwest winds, heavy rain and snow, and cold weather in winter. There are also some proverbs related to Snow Granny circulating among the people, such as "On the 25th of October, the most feared is a strong wind", "If it is sunny on the 25th of October, it will be cold all winter; if it is cloudy on the 25th of October, it will be warm all winter", etc. These proverbs reflect people's attention to and predictions of winter weather.

Snow scene at the Sanwan Scenic Area of ​​the Grand Canal in Yangzhou City, Jiangsu Province (Photo source: Xinhua News Agency)

Snow Granny is mainly responsible for making snow fall. Whenever she beats the mattress or fluffs the pillow, white snowflakes will float in the sky. Her existence is closely related to snow, so she is also regarded as a symbol of winter and snowy days. Zheng Banqiao, a famous painter in the Qing Dynasty, was born in October of the 32nd year of the reign of Emperor Kangxi, which was the "Minor Snow" solar term. According to the local customs of his hometown Xinghua, "Minor Snow" is the day when Snow Granny is born. It is a very auspicious thing for a child to be born on the same day as "Snow Granny". Therefore, the Zheng family also carved a seal with the inscription "Snow Granny was born on the same day".

03Snowflake formation

However, no matter how romantic the legend of Grandma Snow is, it is just a legend after all. So how are snowflakes formed?

Snowflakes are formed when water vapor in the air condenses when it gets cold . The following basic conditions must be met for their formation:

(1) There needs to be a large amount of water vapor in the atmosphere, which is the basis for the formation of snowflakes;

(2) Water vapor needs to condense on condensation nuclei (such as dust, smoke, bacteria, etc.), which provide a point of attachment for water vapor to begin crystallization ;

(3) The air temperature needs to be lowered to a point where water vapor reaches supersaturation , that is, the water vapor content in the air exceeds the saturation water vapor at that temperature. Usually this temperature is below freezing (0°C).

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When the temperature drops and the water vapor reaches a supersaturated state, the water vapor will begin to condense on the condensation nuclei to form tiny ice crystals . This process is called sublimation , which means that the water vapor directly turns into solid ice without going through the process of liquid water. Once the ice crystal is formed, the surrounding water vapor will continue to condense on the ice crystal, causing it to gradually grow.

The growth process of ice crystals includes rapid growth at their corners and protrusions , forming a branching structure. In the cloud, ice crystals will collide and merge with each other to form larger ice crystals or snowflakes. This process is repeated in the cloud until the snowflake grows large enough to overcome the air resistance and buoyancy and fall from the cloud to the ground.

Although the basic shape of a snowflake is a hexagon, each snowflake has its own unique pattern and texture. The formation of these patterns and textures is closely related to the " growth" environment of ice crystals in the cloud, temperature, humidity and other factors.

Temperature is an important factor that affects the shape and size of snowflakes. Different temperature conditions will form snowflakes of different shapes and sizes. At lower temperatures , it is easier to form columnar or needle-shaped snowflakes; at higher temperatures , flakes or star-shaped snowflakes may form.

Humidity also affects the shape of snowflakes. When the humidity is high , water vapor is more likely to condense on ice crystals, causing the snowflakes to grow faster and larger.

Factors such as wind speed, direction, and air pressure in the atmosphere also affect the formation and fall of snowflakes. Therefore, each snowflake is unique, and its shape and pattern reflect the unique environment and conditions during its formation.

Snowflakes have become beautiful works of art in nature due to their unique crystal structure, complex patterns and symmetry, as well as delicate textures and layers. They are also loved by humans, so classic snowy activities such as making snowmen and having snowball fights have emerged. However, although snow is beautiful, you should be careful when playing in the snow.

04 Although snow is beautiful, be careful when playing in the snow

Snow is beautiful. We all go play in the snow when it snows. We must also take precautions when playing in the snow to ensure that we have fun and stay safe while doing so.

Citizens (front right) practice skiing at Beijing Yuyang International Ski Resort. Photo by Xinhua News Agency reporter Ren Chao

♦Before playing in the snow, you should understand the local weather forecast and avoid going out to play in the snow in bad weather such as blizzards, strong winds , etc.

♦ Understand the depth, slope, direction , etc. of the snow field in advance and choose a suitable area for snow play. If the snow field is deep or you need to ski, you should be equipped with suitable ski equipment, such as skis, bindings , etc.

♦Carry a mobile phone with you so that you can call the police or contact others in time in an emergency.

♦ Wear thicker clothing , especially quilted clothing, and outdoor equipment such as hiking shoes, gloves, hats , etc. Clothes should be brightly colored so that they can be easily identified in the snow to avoid collisions.

♦When skiing or doing other snow-playing activities, wear protective gear such as helmets, hip protectors, knee pads, etc. to protect your body from injury.

♦Perform adequate warm-up exercises before playing in the snow, especially on the hip, knee, ankle, wrist and other joints, to reduce muscle viscosity, increase muscle strength and prevent injuries.

♦When playing in the snow, do not chase or play with your friends to avoid slipping or bumping into others and causing injury.

♦When walking in the snow, be careful not to slip, especially on icy roads.

♦Playing in the snow is a physical activity. You should pay attention to maintaining your physical strength and avoid excessive fatigue that may cause physical discomfort.

♦When playing in the snow, you can bring hot drinks or snacks from the ski resort to replenish calories in time.

♦Long-term exposure to low temperature environment can easily cause frostbite . You should pay attention to keeping warm, especially the hands, feet and other parts that are prone to frostbite.

♦If an injury occurs, stop the activity immediately, seek help from others or call emergency services.

♦If symptoms of hypothermia occur, such as a drop in body temperature or chills, you should immediately seek shelter from the wind and cold, take measures to keep warm, and seek medical attention promptly.

Author: Wang Yuanhong, Senior Weather and Climate Engineer

Reviewer: Song Yuanming Associate Professor, Institute of History of Science and Cultural Heritage, University of Science and Technology Beijing, Deputy Director of Institute of Science, Technology and Culture

Produced by: Science Popularization China