◆ Snowflakes fuse many times to form snowflakes.
In fact, the so-called goose feather snow is not a piece of snowflake. Snowflakes have a long journey from the clouds to the ground, and many snowflakes are easy to stick together. This kind of snow is what we call goose feather snow. The diameter of a single snowflake crystal we see falling from the sky is generally 0.5 to 3 mm, but the maximum diameter of snowflakes formed by multiple mergers can reach 65438.
The size of snowflake crystals is closely related to the temperature at which water vapor condenses and crystallizes. The colder the weather, the lower the temperature and the smaller the snowflake crystal. When the weather is very cold, the diameter of snowflake crystals is often less than 0.05 mm. Meteorologists have observed that prismatic ice crystals will be formed when the temperature is between -8℃ and -5℃. When the temperature is -5℃ to -3℃, needle-like ice crystals are formed; When the temperature is -3℃ to 0℃, thin hexagonal plate-like ice crystals are formed. It can be seen that when the temperature is -3℃ to 0℃, the shape of snowflake is the largest and most complete. When the weather is very cold, the snowflake crystals formed are very small and almost invisible to the naked eye. Only when they shine in the sun can people find them as fine powder. This kind of snow is called dry snow.
◆ Heavy snow is not a patent in alpine regions.
Since 1980s, China has been in a warming cycle, and heavy snow with goose feathers is rare in many areas. In people's imagination, it seems that the hometown of "goose feather and heavy snow" is only in the cold area at high latitude and the alpine area at high altitude in winter. However, many articles have pointed out that when the temperature is below 0℃ and close to 0℃, the merging ability of snowflakes is particularly great, and it is easy for many snowflakes to connect with each other to form larger snowflakes. It falls in the form of wet snow This statement further shows that "goose feather snow" is not a patent for high-latitude cold areas and high-altitude mountainous areas, nor is it a patent for the severe winter of 65438+ 10.
During the cold wave cycle in China, not only in the north, but also in the middle and lower reaches of the Yangtze River, there is a large area of heavy snow, which is normal. Since 1980s, China has turned into a warm cycle, but it does not mean that there is no strong cold air in a specific year of the warm cycle. As long as there is stable strong cold air invading China, even in the late autumn and early winter of 165438+ 10, there will be heavy snow.
The better the water vapor condition, the bigger the snowflake will be. We know that the water vapor conditions in the air in the middle and lower reaches of the Yangtze River are much better than those in the middle and lower reaches of the Yellow River. Often the cold air goes south, and the range and amount of snowfall are larger than those in the northern region with low humidity. Sometimes it snows all over the sky, which is very spectacular and even reaches the level of blizzard. In Shouxian County, Anhui Province and Nanjing City, Jiangsu Province, a heavy snow fell in 10. 59660.88868688686
◆ Strong cold air process is easy to form heavy snow.
If it's not cold, it can't snow. Otherwise, even if there is snow at high altitude, it will melt in the air at low altitude because the temperature is higher than 0℃ and fall to the ground in the form of rain. Every year, due to the early influence of cold air in the north, there is snowfall in the north. But we know that clouds are the place where snowflakes are bred, and large-scale deep clouds are the place where large-scale snowfall is bred. Those cold waves or strong cold air with steady steps go south. It provides temperature conditions for the occurrence of heavy snow and even local snowstorms. Strong dry and cold airflow lifts a wide range of warm and humid air to the condensation height, forming a wide and deep cloud layer, which often makes China have a spectacular scene of Wan Li snow drifting and white clothes fluttering from north to south.