How are snowflakes formed?
Snow is a conglomeration of ice crystals formed as a direct change of water vapor contained in the air into ice. The phenomenon of resublimation takes place here. Thanks to the so-called hydrogen bonds, the ice crystal has a hexagonal structure. Its elementary cell (the smallest fragment repeated in the crystal lattice) has the shape of a prism with a hexagon base. Hence the ice crystals have a sixfold axis of symmetry which determines the shape of snowflakes.
Snowflakes are formed in the clouds, where there is a high saturation of water vapor. When the temperature becomes negative and there is some center of crystallization, for example a dust particle or pollen, it begins condensation of water molecules and crystal formation (distilled water due to the lack of fine impurities can be liquid even at -40 ° C).
The flakes formed may have different shapes depending on the temperature and the humidity of the air. Typically, these are six-armed symmetrical stars.
How many sides does a snowflake have
They can also have the shape of flat hexagonal plates, needles, posts, discs and sometimes irregular blocks. First, all the ice crystals grow so snowflake snow flake itself, forming a regular cube. During the journey, the snow flake towards the earth’s surface changes both humidity and ambient temperature. New crystals may be formed on protruding edges that are differently positioned in space than previous forms. Such a process may occur even several times from the moment the snowflake forms up to the point where it touches the ground, which is why snowflakes can have very complex shapes. However, the symmetry is preserved because the distance between the arms of the snow star is so small that each of the arms grows practically at the same temperature and humidity, and this means that it grows in the same way. Because all the crystals formed form a hexagonal (hexagonal) crystal lattice, they have a six-fold axis of symmetry.
At very low temperatures, below -20 ° C, there are no sophisticated star-like shapes in falling snow. On the Earth’s poles there is snow in the shape of columns or flat tiles with a hexagon base. The largest and most beautiful snowflakes arise in the temperature range from -10 ° C to -20 ° C at high humidity. Under these conditions, they take the form of small flakes of 2 to 4 millimeters in size. In general, the higher the humidity, the more ice crystals have more complex shapes. When snowflakes began life in high humidity conditions, and then continued their development, when the water in the air was much less, at first the shapes have complex shapes and as the snow snowflakes move away from the petals, the crystals are simplified. In turn when the growing crystal from the more dry air falls into the wetter area, the further away from its center (from the petal of the petal), the more complex the pattern will be. When the temperature is around -5 ° C and the humidity relatively high, the snow has the shape of needles with a hexagonal cross section, often crossing or being stuck together.
There are not two identical snowflakes, because even the resulting road flakes will never be the same. So the impact of temperature and humidity changes on each of them will be different. In addition, for each petal, the condensation center to which the first water molecules adhere may be different. And from the shape and size of this center depend on the first moments of formation of the snow flake. The second reason is that hydrogen and oxygen occur in nature in different varieties.