The question of why snow is white has been familiar to everyone since childhood. But not all children, and adults, know the correct answer, for which reason small snowflakes are white, and not blue or green. Everyone knows that snow is frozen water, or rather ice. But since ice is transparent and capable of transmitting light through itself, why are snowy snowdrifts that cover the earth far opaque and have a very distinct color?
In past centuries, when there was not yet such advanced technology that allowed us to study all natural processes, scientists struggled over the question of why the snow is white. However, no answer was found. Only when the whole process of creating snow from the very beginning to the end became clear did some speculation about the "snow cover" appear.
It all starts with the fact that under the influence of warm sunlight, water from rivers, lakes and seas turns into steam, and rises high into the atmospheric layers, where permafrost prevails. Steam, in turn, possessing the properties of liquid water, begins to solidify due to the high minus temperature and turns into ice crystals. These are snowflakes that are ready to fall to the ground over time. For the most part, in places where it is warm, the ice falls in the form of wet precipitation, melting in the air.
How snow is formed is now clear, but why, when it falls to the ground, it suddenly turns white?
The question is pertinent, because snowflakes really still in the air have the same transmission properties of light through themselves as ice. But one thing should not be forgotten: the edges of the lenses are located at random angles, which randomly refracts sunlight, and they do not absorb it, but pass it on. And when snowflakes gather in a “snow-white cover”, the rays of the sun, refracting from one snowflake to another, pass through the entire cover. Many rays are reflected in our eyes, which is why often, when you look at the snow, you have to squint. Sunlight is too bright to be perceived by unprotected eyes.
But it’s not quite right to ask the question of why the snow is white, because it is not always “clean”. This is how people see him only when rays of sunlight fall on him. For example, at sunset it can turn a pinkish tint, and in the light of a yellow lantern it can be slightly sandy, just like in cloudy weather its shade can be grayish.
Changes in the color of snow are also possible in the air layers, when snowflakes are just starting their “fall on the ground". For example, various pollen from trees and flowers, dust from arid land rises and meets with particles of snow in air currents. If such snow does not have time to melt and remains a small cover, then its color will certainly be with different shades. In these conditions, asking why the snow is white is inappropriate.
However, snowflakes are not just icicles flying chaotically down, which for some reason decided to cover the ground with a “white blanket”.
The main properties of snow is to protect the earth from cold weather, covering it with a thick blanket. Yes, it would seem paradoxical to warm and preserve the crop and soil from freezing, but it’s true. It has poor thermal conductivity, allowing it to restrain the heat leaving the earth and create a “thermal cushion”. No wonder that the needle was built by the inhabitants of the far north. Ice, like snow, holds heat well, creating unique favorable conditions for life.
Do not lose sight of the fact that the size of the snowflakes depends on the weather outside the window. If it's cold enough, then the ice is small, almost imperceptible. But if the sun is shining and the air is not so cold, then the size of a snowflake can reach several centimeters. So, in 1944, ten-centimeter “ice particles” fell out in Moscow.