Snow is a type of precipitation that is characteristic of a particular season of the year. Falling down, they grow, building up their body due to condensation on their parts of air and moisture. The size and lace of falling snowflakes depends on the height and temperature of the cloud from which they formed. But why does snow creak underfoot in cold weather?
To understand why the snow creaks underfoot in the beginning it is necessary to understand the structure of the snowflake.
Snowflake texture
The molecular structure of water is arranged in such a way that the angles in the formation of snowflakes can be only 120 and 60 degrees. At the edges and tops of the snowflakes, new crystalline growths form, on top of them the following layers freeze. As a result of these processes, various amazing forms are born, but almost all resemble the shape of a star.
The main forms of snowflakes
Scientists have identified several basic forms of snowflakes:
- A needle - a crystal resembling a long needle made of ice, is sometimes hollow, and the ends branch out into several growths;
- Star - formation resembles the weaving structure of ice fibers. Fibers are usually located in arbitrary branching;
- Dendrites - formed during the fusion of crystals of snowflakes, forming symmetrical branching growths;
- Fluffy - snowflakes that have lost some parts along the way or have completely broken. This happens for several reasons, one of them is a strong wind;
- Column - large flat snowflakes, are the most common, resembling the shape of a column or pencil, usually hexagonal, pointed at the end;
- Plate - come in the form of a petal, which is divided into sectors by ice ribs.
What determines the shape of snowflakes?
Among these groups, 48 different types of snowflake formation are distinguished. The shape of snowflakes directly depends on the environmental conditions in which it is formed. First of all, the silhouette of a snowflake is affected by temperature, the cloud is colder the higher it is. If the temperature of the cloud is relatively high - 30 to 0, then the formation of a snowflake will resemble a hexagon with a flat body. At temperatures from - 5 to - 3 degrees, snowflakes resemble needle-shaped crystals. From - 8 to - 12, the shape again resembles a flat hexagon, and at temperatures from - 13 to - 16 snowflakes form in the form of crystalline stars.
Why is snow creaking?
As described above, snow is the formation of various crystals of small sizes. In the body of a snowflake, among the crystals there is also air. When a certain amount of snow is compressed, it becomes denser, the entire composition of the air is displaced, and the snowflake crystals break apart. PDuring friction and fracture, the crystal makes a sound that is perceived by the human ear as a crunch or creak. This noise is not always heard.
Why does snow creak in cold weather but not in warm weather?
At elevated temperatures, a part comes, and water suppresses the noise of crystal fracture; therefore, this sound is clearly audible only in frosty weather.Due to the temperature difference, a certain amount of water is present on the snow surface, this contributes to the freezing of snowflakes in its layer. In recent snow, the density between snowflakes is low, while in old snow it is high. Such snow is also capable of making sound when compressed, but already lower. Here the sounds are more like not a creak, but a dull rustle.
The sound of snow creaking can be louder or quieter. The lower the air temperature, the louder the snow will hold together. In the far north, where the air temperature reaches - 50 degrees, a crunch of snow can be heard in a radius of several hundred meters, the sound frequency is from about 1 thousand to 1600 Hz. At elevated temperatures, snowflake crystals begin to melt, forming water around them. Water drowns out the sound of friction of crystals, and the snowflake itself is no longer so fragile. When squeezing snow, snowflakes now not only break, but also crumple under the influence of water. The creaking of thawed snow is much quieter, its frequency in the region of 250 - 400 Hz. Above -6 degrees, the creak becomes noticeably quieter.
Snowflakes form in the cloud, where water particles accumulate around small dust particles and then the process of growth of ice crystals begins. Snowflakes come in different shapes and patterns, which are influenced by various factors, such as the height of formation and air temperature. When the snow is compressed, the snowflake crystals break and rub against each other, as a result of this, the sound of a creak or a crunch of snow is heard.
