Buzz
Snow consists of countless individual ice crystals that come together to form a blanket of white. Photo by Baac3nes/Moment/Getty ImagesOne reason we all enjoy snow is its ability to cover everything in a seemingly "pure" white layer. Phrases like 'some of the white stuff' are often used in weather forecasts, and around December, the song 'White Christmas' fills the air year after year.
Snow wouldn’t be snow without its characteristic whiteness. But it’s curious that snow is white, given that it’s made up of ice crystals. To understand this, we need to delve into the reason why objects appear in different colors in the first place.
Where Do Colors Come From?
Visible light consists of various vibration frequencies that our eyes interpret as different colors. Essentially, the particles' electrons vibrate at different rates in response to the energy they absorb, based on the energy's frequency.
When it comes to light energy, molecules and atoms absorb specific amounts of light depending on its frequency, and then release this energy in the form of heat. As a result, some objects absorb certain light frequencies more than others.
For light frequencies that aren't absorbed, different things can occur. In some materials, when a particle releases the absorbed photons, they pass right through to the next particle. This allows light to travel completely through the material, making it transparent.
In most solid materials, particles release the majority of unabsorbed photons back out, meaning little to no light passes through, leaving the object opaque. The color of an opaque object is simply the combination of the light energy that its particles didn’t absorb.
Why Snow Appears White
There’s a lot of scientific reasoning behind why snow is white. However, this dog couldn’t care less, as it’s simply enjoying the snow. Photo by Willowpix/Getty ImagesAlthough snow is frozen water, and we all know that pure frozen water is clear, why does snow have its unique white appearance? To explain this, let’s examine a piece of ice. Ice is not fully transparent; it is in fact translucent. This means light photons don’t pass through in a straight line but instead get redirected by the particles within the material.
This occurs because the distances between some atoms in the ice’s molecular structure are close to the size of light’s wavelengths. As a result, the photons interact with the ice, causing them to change direction, so they exit the ice at an angle different from how they entered.
Snow is made up of numerous individual ice crystals that are grouped together. When a photon of light enters the snow, it passes through the first ice crystal, which slightly redirects it and sends it toward another crystal, which does the same thing.
In essence, the crystals scatter the light in all directions, causing the light to eventually exit the snow. This scattering happens with all the different light frequencies, so all colors are reflected back out.
The combined color of all visible light frequencies in equal amounts appears as white, which is the color we perceive in snow, even though white isn’t the color we observe in the individual ice crystals that make up the snow.
Indeed, snow can appear bluish-white or pinkish-white depending on the angle of the sunlight or if it’s in shadow (or yellow if a nearby dog has been playing in it), as the National Center for Atmospheric Research points out. Snow can even turn red when it’s teeming with algae.
