Why is Snow White When Water is Colorless?
One of the reasons we all love snow is that it covers everything with a clean, pure, white veil. But if you think about it, it’s a strange situation to have the snow-white. In essence, the snow is a cluster of ice crystals sticking together. It is made of water and the water is colorless. So why is snow white?
To understand the answer to this question, we first have to understand what white is, then we must understand why different things have different colors. You may have heard people say that white light is a combination of all colors. However, some will say that white is the absence of color. For example, we use bleach to remove and whiten all other colors from your clothes. So how can white be both a combination of all colors and colorless? The answer lies in the fact that we are talking about two different concepts. These are white light and white objects.
What is White Light?
The white light that comes to us from the sun is a mixture of all possible colors, all visible wavelengths. Since sunlight is our natural light, we call it white, in fact, white light is colorless light for the human eye. But in 1666 Sir Isaac Newton discovered that this neutral light could be split into a rainbow of component colors simply by passing it through a triangular prism. He later proved to us that all these colors really exist in the original white light by recombining them.
Newton thought it would be a good idea to divide the entire rainbow, or spectrum of colors, into seven categories that resemble seven musical tones in an octave. He chose red, orange, yellow, green, blue, indigo, and violet for the color categories. And we learned this in schools as “the seven colors of the rainbow”.
In reality, there is an infinite number of colors visible and invisible to the human eye in the light of the sun, just as there is an infinite number of possible musical hues. Visible light consists of different light frequencies. Our eyes perceive different frequencies as different colors. This is because the particles that make up the object have different vibration frequencies. These particles absorb a certain amount of light energy depending on the frequency of the light and then emit this absorbed energy as heat. A few different things can happen to frequencies of light that are not absorbed.
In some materials, when a particle re-emits photons, they continue to move on to the next particle. In this case, the light reaches all over the material so the material is clear. In most solid materials, the particles re-reflect most of the photons from the material, so no light passes through and the object is opaque. Unlike white light, when white light falls on a white object, it reflects all colors equally to our eyes without changing the light mixture. So what we choose to call “white” looks like the same “color” as the light falling on it. So the object does not contribute to its own color. But colored objects do indeed add to their color. Its molecules selectively absorb and retain certain colors of sunlight, reflecting others back as a modified mixture.
White Shirt – Red Cape
Imagine an actor wearing a red cloak over a white shirt on stage. If you shine a red spotlight on it, it will appear red all around and the white color will disappear. The only light that any part of his costume can project to us is red. Now hold a white spotlight on it. The red cape still appears as red, while the white shirt is white so the colors do not change because the white spotlight does not absorb any of the colors.
Why Is Snow White?
Since snow is frozen water and we all know that frozen water is clear, why does snow have a distinctive color? Snow is a lot of ice crystals standing together. When a light photon enters a layer of snow, it passes through an ice crystal at the top and slightly changes its direction and sends it to a new ice crystal, and so on. Basically, all crystals reflect light all around so that eventually the light comes back from the snowdrift. This is true for all different light frequencies, ie all light colors are reflected back. The “color” of all frequencies in the equally combined visible spectrum is white, so this is the color we see in the snow, whereas it is not this color we see in snow-forming ice crystals.