Snowflakes, capable of attracting adults and children, have always fascinated us with their shapes and ability to cover everything around with a muffled white blanket. But how are they formed What science explains this very remarkable phenomenon?
In the meantime, we need to start with a clarification: those we call generic “snowflakes”Symmetric, with six arms and all different, they are actually crystals. “Flakes” is a more general term, it refers to everything we see falling from the winter clouds. It could be a single crystal, or groups of hundreds or even thousands of them, colliding and staying together in mid-air.
When raindrops freeze, they form the cold. On the other hand, ice crystals form when water vapor in the air turns directly into ice without first turning into liquid water, around tiny dust particles in the air. A star snow crystal begins its formation with a small hexagonal plate — the hexagonal core linked to the arrangement of the water molecules in it — which grows and develops as more water vapor condenses onto the nascent crystal. At this point its ornate patterns emerge from the six corners: as it descends through the clouds, it experiences ever-changing temperatures and humidity, each change causing the arms to grow slightly differently. Its shape is determined by the exact path it took, So no two can be found alike!
In addition, the arms grow independently, albeit under the same conditions, so they end up having very similar shapes. When the temperature or humidity changes around the crystal, all six branches change their growth synchronously, While they do not communicate with each other. Even if we used to think that crystals are all the same from the cool pictures you can find on the Internet, in fact, irregular pictures are the most common. According to some studies done to understand the temperature and humidity ranges in which different types of structures develop, needles form around -5°C mainly, between -10°C and -20°C branching structures and below -20°C leaflets, flat or in the form of a column. In terms of size, they range from the smallest crystals about the same diameter as a human hair to the largest crystals ever photographed measuring a centimeter from tip to tip.
Given that water vapor is colorless – and water is transparent – it is natural to ask cHow is snow white?. A body is transparent – as in the case of water – if light passes through it, it is colored if it partially absorbs it, partially reflects it, and it is black if it absorbs all the light that strikes it. But in the case of ice crystals, what happens? If the single is still transparent, the many hues in the different crystals crossed by the rays of light cause them to be deflected and reflected in all directions: in this way all the colors which the original rays of light were made of. Therefore, the perceived color is exactly the sum of all of them, that is, white. Because snow reflects almost all of the light present, it is often dazzling, especially on sunny days. If the snow begins to melt, the crystal structure will lose the cohesion typical of ice and will absorb light more easily, gradually returning to transparency like water. On the other hand, ice has a different, more organized structure, and it can also take on a blue color depending on its thickness.
The impression that snow makes everything muffled is not a subjective thing: Snow really creates silence, and there is a scientific explanation. When the crystals fuse together to form flakes, they capture air and organize it into spaces that actually absorb sound, muffling it, making it bounce back easily. This effect increases when it is colder: with the lowest temperatures, in fact, the snow is more intense, at 0 ° C 25 mm of rain produces 25 cm of snow, while if it drops to -6 ° C the thickness of the snow can It reaches up to 50 cm and absorbs any noise.
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