Why Snowflakes Have Many Shapes Why Snowflakes Have Various Shapes

When we think of snow, we think of a white patch. Since snow can easily turn into snow water as soon as it falls on us, few people have really looked at it closely.

More than 4,000 shapes have been discovered to date, but the most basic ones are sheet, columnar, and star-shaped. When the extremely small ice crystals and supercooled water droplets below 0 form a cloud, the water vapor continues to rise and the ice crystals condense, and the water temperature reaches -5, countless hexagonal ice needles are formed. This is the most stable shape of ice crystals.

At the same time, the effect of condensation continues.

If there is a lot of water vapor around the ice crystals, the six corners grow rapidly and form a star;

If there is very little water vapor around the ice crystal, and the six corners do not grow as fast as the two bottom surfaces, a columnar shape will be formed. If the moisture is moderate, flaky snowflakes will form.

If the surrounding air is less saturated, the ice crystals will grow very slowly and evenly on all sides. As it grows and falls, it retains its original appearance and is called columnar, needle-shaped, and flake-shaped snow crystals, respectively.

If the surrounding air is highly supersaturated, the ice crystals will not only increase in volume but also change shape as they grow. The most common is to change from flakes to stellate.

Considerable parts of the snowflake, regardless of shape or size, should be the same. This typical stellate snowflake can only form in an ideal, calm environment, such as in a laboratory. In the atmosphere, it cannot grow in as systematically as mentioned above, and the shape it forms cannot be as typical.

This is because the ice crystals are gradually descending and sometimes rotating, and the branches that are exposed to water vapor vary from branch to branch, and those that are exposed to more water vapor grow more. As a result, the snowflakes we usually see are largely the same, but they are not the same.

In addition, as snowflakes fall within the clouds, they also fall from an environment suitable for one shape to an environment suitable for another shape, so various complex snowflake shapes can be seen. Some are like cufflinks, some are like thorns. Even if they are all star-shaped snowflakes, there are three branches, six branches, even twelve branches, and eighteen branches.

All of the above are the case for individual snowflakes. As the snowflakes fall, the individual snowflakes can easily cling to each other and merge together to become larger flakes. The combination of snowflakes is mostly seen in the following three situations.

1) When the temperature is below 0, the snowflakes collide on the way down slowly. The pressure and heat generated by the collision caused some of the colliding parts to melt and stick to each other, and then the melted water immediately froze again. In this way, the two snowflakes merge together.

2) When the temperature is slightly higher than 0, the snowflakes are already covered with a layer of water, and if the two snowflakes touch, they will be bonded together by the surface tension of the water. (3) If the branches and forks of the snowflakes are complex, the two snowflakes can also be hung together by simply climbing.

This has to do with the crystallization habit of water. The crystallization properties of natural frozen ice and snow crystallized by water vapor condensation in the atmosphere belong to the hexagonal crystal system. The hexagonal crystal system has four crystalline axes—one major axis plus three auxiliary axes.

The three auxiliary axes are distributed in the same plane and intersect each other symmetrically at an angle of sixty degrees. As for the main crystal axis, it is drawn from the intersection of the three auxiliary axes, and the well is perpendicular to the plane formed by the auxiliary axes. The most typical representative of the hexagonal crystal system is a regular hexahedral cylinder in geometry.

When the water vapor is crystallized, if the main crystal axis develops slower and shorter than the other three auxiliary axes, then the shape of the snow becomes hexagonal snow flakes, and if the main crystal axis develops quickly and the extension is longer, then the shape of the snow becomes hexagonal. The temperature in the atmosphere plays a large role in the shape of snowflakes. If the temperature is high, it is easy to produce hexagonal snow flakes, and if the temperature is low, it is easy to produce columnar snow crystals.

According to the observations and studies of many scientists, when the atmospheric temperature is below -25, the shape of snow is mostly hexagonal prism with the main crystal axis developing. At temperatures of -25 -15, the crystals of the snow are mostly hexagonal flakes; When the temperature is -15 0, most of the snow in the sky is beautiful six-pointed star-shaped.

The conditions for the formation of snowflakes are very different, and the shape of snowflakes is mainly related to the temperature at which the snowflakes are formed, when the temperature is -3 to -8, the snowflakes are needle-shaped; At temperatures from -8 to -25, the snowflakes are flakes or fan-shaped; No matter how cold it gets, the snowflakes become jade columns, so snowflakes come in a variety of shapes. <

The conditions for the formation of snowflakes are very different, and the shape of snowflakes is mainly related to the temperature at which the snowflakes are formed, when the temperature is -3 to -8, the snowflakes are needle-shaped; At temperatures from -8 to -25, the snowflakes are flakes or fan-shaped; No matter how cold it gets, the snowflakes become jade columns, so snowflakes come in a variety of shapes.

Snowflake, also known as silver millet, jade dragon, jade dust, is a kind of crystal, is the water vapor in the sky through the condensation of solid precipitation, the structure changes with the change of temperature, mostly hexagonal, like flowers. Most of the snow sedan flowers are hexagonal, because the snow belongs to the hexagonal crystal system. The Xiaoice crystals of the "embryo" of snowflakes in the clouds are mainly of two shapes.

One is hexagonal, long and thin, called column crystal, but sometimes its ends are pointed, like a needle, called needle crystal. The other is in the form of hexagonal flakes, like the thin slices cut from the hexagonal pencil, called flakes.

Related to the speed of water vapor condensation crystallization, snowflakes are changed by the increase of Xiaoice crystals, and the ice molecules are hexagonal as the most auspicious, so the formation of snowflakes is mostly hexagonal. The variety of snowflake shapes is closely related to the water vapor conditions at the time of its formation.

Thermal insulation: <>

1. The snow, like a wonderful carpet, is spread on the earth, so that the ground temperature will not fall too low due to the severe cold of snowflakes in winter. This thermal insulation effect of snow cover is inseparable from its own characteristics;

2. The snow covering the earth's chest is very similar to cotton, and the porosity between the snowflakes is very high, which is the layer of air drilled into the pores of the snow, which protects the ground temperature from falling very low;

3. The heat preservation function of snow is changing with its density. It's much like when a new padded jacket is particularly warm, but an old padded jacket is not so warm;

4. The density of fresh snow is low, and there is more air stored in it, and the heat preservation effect is particularly strong;

5. Old snow is like an old cotton jacket, with high density, and the air hidden in the storage chain is less, and the thermal insulation effect is weak.

The variety of snowflake shapes is closely related to water vapor conditions.

In the case of the same water vapor pressure, the condensation growth of ice crystals is also different due to the different saturated water vapor pressures on the surface, edges and corners of ice crystals. If the water vapor in the cloud is not too abundant, the water vapor pressure is only greater than the saturated water vapor pressure of the plane, and the water vapor only condenses on the surface, and the formation is a columnar snowflake; If there is a little more water vapor, the water vapor pressure is greater than the saturated water vapor pressure on the side reed, and the water vapor will condense on the edge and on the surface, because the speed of condensation is also related to the degree of bending, the condensation is faster in places with a large degree of bending, so the condensation on the edge of the ice crystal is faster than on the surface, and more flakes are formed at this time; If the water vapor in the cloud is very abundant, the water vapor pressure is greater than the saturated water vapor pressure on the corner, so that there are water vapor condensation on the surface, edge, and corner, but the position at the sharp corner is prominent, the water vapor ** is the fullest, and the condensation grows the fastest, so it forms more branch-like or stellate snowflakes.

In addition, the ice crystals are constantly moving, and the temperature and humidity conditions in which they are exposed are constantly changing, so that the various parts of the ice crystals grow at different rates, forming a variety of snowflakes.

Snowflakes actually have only 35 normal shapes. These shapes, including columnar ice crystals, irregular snow particles, and flat crystals, make up the "traditional" hexagonal snowflakes. Bird Minning.

This chart shows 39 types of "solid precipitation" or snow, including 35 species of snowflakes and their names. The 39 intermediate crystal families were further divided into 8 groups, namely columnar ice crystals, flat crystals, columnar ice crystals and flat crystal mixtures, snow crystal aggregates, frost snow crystals, ice crystal germs, irregular grains, and fern-like shapes. Columnar ice crystals and flat crystals are the shape of snowflakes that many people imagine.