If the water or ice is transparent, why is the snow white? Most of us recognize that water, in its pure form, is colorless. Impurities, such as mud in a river, allow the water to acquire other shades.
In the case of snow, it can also acquire other shades, depending on certain conditions. Thus, when the snow compacts, it can take on a blue hue, very common in the blue ice of glaciers. But white or blue are not the only colors for snow or ice. Algae can grow on snow, making it appear more red, orange, or even green in color. We will remember having read about the “watermelon snow”, caused precisely by a type of cold-loving algae that lives inside the snow layer, coloring the snow with this unusual tincture.
The impurities in the snow -like the example we mentioned before-, therefore, will make it appear to be of a different color, such as yellow (I think it is no mystery to anyone to see yellow snow; if you see it, have for sure there are animal tracks nearby) or brown. Dirt and debris near a road can make snow appear gray or even black.
Where does it get its distinctive color from?
Despite these colorations, the best known feature of snow is its snowy color. Where then does its whiteness come from?
We must remember that visible light is made up of many different light frequencies. Our eyes detect these frequencies as colors. Objects have different colors because the particles that make up the object have different frequencies of vibration. In the case of light energy, molecules and atoms absorb a certain amount of energy depending on the frequency of the light and then emit this absorbed energy in the form of heat. This means that some objects absorb certain frequencies of light more than others.
So if snow is transparent, why is it colored? Understanding the physical properties of snow and ice helps us understand the color of snow. It turns out that ice is not transparent, but translucent, which means that photons of light do not pass through the material directly; rather, the particles in the object change the direction of the light. The result is that the path of the light photon is altered and exits the ice in a different direction than it entered the ice. Taking into account that snow is nothing but a bunch of tiny ice crystals – of different shape and structure – united, when a photon of light enters a layer of snow, it passes through an ice crystal at the top, which slightly modifies steering, sending it to a new ice crystal, which does the exact same thing.
In essence, all ice crystals bounce light everywhere. It does the same with all the frequencies of light (red, orange, yellow, green, blue, indigo and violet) and the “color” of all the frequencies combined in the visible spectrum gives us the color white, so this It is the color that we see in the snow . That is why our eye “sees” white when we look at the snow, because part of the light that falls on the snow is scattered equally in all spectral colors and, since white light is made up of all the colors of the visible spectrum, we see the white snowflakes.
But no one sees one snowflake at a time. Usually we see millions of snowflakes covering the ground. As light hits the snow on the ground, there are so many places for the light to be reflected that no single wavelength is constantly absorbed or reflected.
