Snowflakes are formed in clouds. It turns out that when ice crystals grow, they consume nearby water vapor. Therefore, the closer to the ice crystals, the thinner the water vapor is, and the water vapor further away naturally comes to replenish it. They first encounter The sharp corners are extending forward. As a result, each sharp corner quickly lengthens and gradually becomes branch-like. For the same reason, new twigs grow on these "branches", and over and over again, the hexagonal snowflakes we see are formed.

The shapes of snowflakes vary greatly, and each snowflake is a delicate work of art. By now, it is known that snowflakes have 20,000 different patterns. But it's basically hexagonal. At the beginning of the last century, Dr. Ukichiro Nakatani, a Japanese physicist who conducted special research on ice and snow, once compared snow to a "messenger from the sky" and found out that the crystallization forms of snow vary widely depending on the temperature of the upper air and the amount of water vapor. Now, Associate Professor Yoshijun Furukawa of Hokkaido University's Low Temperature Research Institute, as the successor of Dr. Nakatani, is conducting in-depth research on the crystal shape of snow.

Snowflakes do not produce themselves out of thin air. They must rely on invisible dust particles in the air below the stratosphere as crystal nuclei, surrounded by water molecules of water vapor under the action of cold air. It condenses layer by layer, and the crystal nucleus grows outward from the center. It takes about 5 minutes to form a snow crystal. During this time, the airflow in the snowmaking environment is always rising and falling, turbulent, but the water vapor must maintain an equal amount of action on the periphery of the crystal nucleus. The thickness, humidity, and temperature of clouds in the sky have a great impact on the shape of snowflakes. The formation of star-shaped snowflakes requires greater humidity, while clouds with lower humidity are prone to forming flaky and powdery snowflakes. In fact, individual snowflakes are extremely small, with a diameter between 0.5-3mm. 5,000 snowflakes weigh less than 1 gram on a precision balance. They are very beautiful when viewed under a microscope. The quality of ordinary water depends on the heavy water content. A high content will lead to poor water quality. On the contrary, the water quality will be better. Usually, 7 kilograms of water contains 1 gram of heavy water, while 7 kilograms of snow water only contains 0.25 grams of heavy water. It can be seen that the biochemical properties of snow water are much better. If there is plenty of snow and water, the wheat fields will grow well in spring. When soaking seeds in spring plowing, the proportion of heavy water is large and the germination rate is low. If the seeds are soaked in snow water, they will be like a fish in water.

Clouds are the place where snowflakes are born. Snowflakes are produced from these small crystal nuclei in the clouds. There are three trends in the growth of crystal nuclei: long and thin hexagonal prism-shaped crystal pillars, and the two ends are pointed like a stick. needles and very thin hexagonal wafers. If the concentration of water vapor around them is low, the ice crystals will grow slowly and evenly on all sides; if the concentration of water vapor around them is high, not only will the volume increase, but the shape will also change during the growth process. The most common one is Hexagonal snowflakes falling in the sky. Why do they tend to be hexagonal? The ice crystals before forming snowflakes are affected by the surrounding environment. The growth rates of the regular hexagonal crystals on the bottom and the cuboids on the sides are different, and the shapes also change accordingly. For example, the temperature will bring subtle changes to the surface of the crystal, which is close to 0°C. When the temperature drops to -5°C, the bottom surface expands horizontally into a hexagonal shape, forming a needle shape at -5°C. When the temperature drops to -5~-10°C, regular hexagonal prisms and hexagonal prisms with hollow sides begin to form on the sides. At -15°C, a regular hexagonal prism begins to form. When the temperature drops to -10~-21°C, the regular hexagon begins to expand again and then regenerates into a hexagonal prism. When there is less surrounding water vapor, the generation process is slower and complex shapes are less likely to appear. On the contrary, the greater the water vapor content, the faster the generation speed and the more complex the shape. The dendritic snow crystals known as "snowflakes" are often formed in an environment containing a large amount of water vapor at around -15°C. Although the rate at which crystals form depends on temperature and water vapor concentration, other gases in the air can also affect their formation. Experiments have shown that almost all ice crystals formed in a vacuum space with only water vapor have single triangular prisms, while crystals formed in the sky show needle-like and hexagonal prism shapes. Computer calculations can reproduce the shape of ice crystals extending in six directions, but the reason why they branch in the middle and appear dendritic has never been explained. As shown in the photo, the mechanism of the wonderful point-symmetric branching method is still unknown to this day. It's a mystery.