Speaker 1: Welcome to brain Stuff, a production of I Heart Radio,
Speaker 1: Hey brain Stuff, Lauren Bogle bomb here. One of the
Speaker 1: reasons that people love snow is that it coats everything
Speaker 1: in a blanket of dazzling white weather. Reporters will say
Speaker 1: that we might be getting some of the white stuff,
Speaker 1: and every December you're likely to hear the song White
Speaker 1: Christmas over and over again. But if you think about it,
Speaker 1: it seems weird that snow is white at all, since
Speaker 1: it's just a bunch of ice crystals stuck together. So
Speaker 1: where does it get its distinctive color. To understand where
Speaker 1: this whiteness comes from, we need to back up and
Speaker 1: look at why different things have different colors. In the
Speaker 1: first place, visible light is made up of many different
Speaker 1: frequencies of light. Our eyes detect different frequencies as different colors,
Speaker 1: and different objects have different colors because the particles that
Speaker 1: make up the object, it's atoms and molecules, react differently
Speaker 1: to different frequencies or colors of light. The molecules and
Speaker 1: atoms absorb a certain amount of light energy depending on
Speaker 1: the frequency of the light, and then emit this absorbed
Speaker 1: energy as heat. This means that any given object absorbs
Speaker 1: certain frequencies of light more than other frequencies. A couple
Speaker 1: of different things can happen to the light frequencies that
Speaker 1: are not absorbed in some material. When a particle re
Speaker 1: emits the photons, they continue to pass through to the
Speaker 1: next particle. In this case, light travels all the way
Speaker 1: through the material, which means the material will appear to
Speaker 1: be clear, like a flat piece of glass. However, in
Speaker 1: most solid materials, the particles re emit most of the
Speaker 1: unabsorbed photons back out of the material, so that no
Speaker 1: light or very little light passes through and the object
Speaker 1: appears opaque. The color of an opaque object is just
Speaker 1: the combination of the light frequencies that the objects particles
Speaker 1: did not absorb, though the re emitted light can be
Speaker 1: to stored it on the way out, and that is
Speaker 1: why although ice is mostly clear, snow is mostly white.
Speaker 1: Let's back up again and look at an individual piece
Speaker 1: of ice. Ice is not transparent. It's actually translucent. This
Speaker 1: means that the light photons don't pass right through the
Speaker 1: material and a direct path the materials particles change the
Speaker 1: light's direction. This happens because the distances between some atoms
Speaker 1: and the ice is molecular structure are close to the
Speaker 1: height of light wavelengths, which means the light photons will
Speaker 1: interact with those structures. The result is that the light
Speaker 1: photons path is altered and it exits the ice in
Speaker 1: a different direction than it entered The ice. Snow is
Speaker 1: a whole bunch of individual ice crystals arranged together. When
Speaker 1: a light photon enters a layer of snow, it goes
Speaker 1: through an ice crystal on the top, which changes its
Speaker 1: directions slightly and sends it onto a new ice crystal,
Speaker 1: which does the same thing. Basically, all of those crystals
Speaker 1: bounced the light all around so that it comes right
Speaker 1: back out of the snow pile. It does the same
Speaker 1: thing to all of the different light frequencies, so all
Speaker 1: colors of light are bounced back out. The color of
Speaker 1: all the frequencies in the visible spectrum combined in equal measure,
Speaker 1: is white. So this is the color that we see
Speaker 1: in snow, while it's not the color that we see
Speaker 1: in the individual ice crystals from that snow. Today's episode
Speaker 1: was written by Alice in mould Our Milk and produced
Speaker 1: by Tyler Clang. For more on this and lots of
Speaker 1: other colorful topics, visit how stuff works dot com. Brain
Speaker 1: Stuff is production of iHeart Radio or more podcasts My
Speaker 1: heart Radio visit the iHeart Radio app, Apple Podcasts, or
Speaker 1: wherever you listen to your favorite shows.