It’s easy to just say “snow”

4 questions and peculiarities that perhaps you don’t know

Snow is the iconic symbol of mountains in winter. When it falls in the Dolomites, it cloaks the trees and softens the contours of slopes, from which dark mountain peaks rise up, creating a fascinating contrast. Immersed in this enchanted landscape, you are taken back to your childhood and want to throw snowballs or whizz down a slope on a sled. However, if you stop and think about it, snow is something extraordinary and mysterious. For instance, have you ever wondered why it is white? Or how it seems to create a calming silence? And also, is it true that no two snowflakes are exactly the same? Here are the answers to the most interesting scientific peculiarities about snow, the Winter Queen in the Dolomites.

Why is snow white?

"It cloaks the trees and softens the contours of slopes"

1. Why is snow white?

Individual snow crystals, just like the water they are composed of, are transparent. However, every time a ray of light crosses a crystal it is slightly refracted. After countless refractions, light emerges from the mantle of snow in all its colours. When it reaches our eyes, we perceive it as being white because white is the combination of all colours. Finally, since almost all the light is reflected, snow seems very bright or even dazzling.

2. Is it true that no two snowflakes are exactly the same?

It is easier to win the lottery than to find two identical snowflakes. A flake, in fact, is formed when some droplets of cold water combine with a dust particle, creating a hexagonal crystal. As drops combine onto this nucleus, an intricately branched geometric crystal structure is formed. It has been calculated that, ultimately, a snow crystal contains about a billion billion drops of water. It is therefore practically impossible to find two crystals with an identical structure: each flake is unique and unreproducible.

Why is snow white?

"White is the combination of all colours"

3. How does it dampen noise?

The secret lies in the large-shaped crystals, which leave plenty of space between one flake and another. Air slips into these gaps and absorbs sounds, preventing sound waves to be propagated to our ears. Noise is therefore muffled and this increases when temperatures drop because snow is fluffier and therefore there is more space to absorb noise. However, the insulating effect disappears as soon as the snow is compressed.

4. Why isn’t there thunder and lightning when it snows?

Indeed, there can also be thunder and lightning when its snows, but it is less frequent than in summer storms. In fact, in winter, the ground does not warm up sufficiently to create the unstable atmospheric conditions that cause storms. Nevertheless, when a cold air current from the polar regions clashes with the warmer air south of the Alps, the latter may be pushed to higher altitudes, where it forms cumulonimbus clouds that can produce a ”thundersnow” with lots of thunder and lightning. It is difficult to see such a phenomenon because, besides being a rare event, snow dampens the noise of thunder, which can no longer be heard at a distance greater than two or three kilometres.

Published on 14/11/2019