WEBVTT - Why Is Snow White?

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<v Speaker 1>Welcome to brain Stuff, a production of I Heart Radio,

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<v Speaker 1>Hey brain Stuff, Lauren Bogle bomb here. One of the

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<v Speaker 1>reasons that people love snow is that it coats everything

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<v Speaker 1>in a blanket of dazzling white weather. Reporters will say

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<v Speaker 1>that we might be getting some of the white stuff,

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<v Speaker 1>and every December you're likely to hear the song White

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<v Speaker 1>Christmas over and over again. But if you think about it,

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<v Speaker 1>it seems weird that snow is white at all, since

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<v Speaker 1>it's just a bunch of ice crystals stuck together. So

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<v Speaker 1>where does it get its distinctive color. To understand where

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<v Speaker 1>this whiteness comes from, we need to back up and

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<v Speaker 1>look at why different things have different colors. In the

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<v Speaker 1>first place, visible light is made up of many different

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<v Speaker 1>frequencies of light. Our eyes detect different frequencies as different colors,

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<v Speaker 1>and different objects have different colors because the particles that

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<v Speaker 1>make up the object, it's atoms and molecules, react differently

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<v Speaker 1>to different frequencies or colors of light. The molecules and

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<v Speaker 1>atoms absorb a certain amount of light energy depending on

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<v Speaker 1>the frequency of the light, and then emit this absorbed

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<v Speaker 1>energy as heat. This means that any given object absorbs

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<v Speaker 1>certain frequencies of light more than other frequencies. A couple

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<v Speaker 1>of different things can happen to the light frequencies that

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<v Speaker 1>are not absorbed in some material. When a particle re

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<v Speaker 1>emits the photons, they continue to pass through to the

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<v Speaker 1>next particle. In this case, light travels all the way

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<v Speaker 1>through the material, which means the material will appear to

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<v Speaker 1>be clear, like a flat piece of glass. However, in

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<v Speaker 1>most solid materials, the particles re emit most of the

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<v Speaker 1>unabsorbed photons back out of the material, so that no

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<v Speaker 1>light or very little light passes through and the object

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<v Speaker 1>appears opaque. The color of an opaque object is just

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<v Speaker 1>the combination of the light frequencies that the objects particles

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<v Speaker 1>did not absorb, though the re emitted light can be

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<v Speaker 1>to stored it on the way out, and that is

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<v Speaker 1>why although ice is mostly clear, snow is mostly white.

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<v Speaker 1>Let's back up again and look at an individual piece

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<v Speaker 1>of ice. Ice is not transparent. It's actually translucent. This

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<v Speaker 1>means that the light photons don't pass right through the

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<v Speaker 1>material and a direct path the materials particles change the

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<v Speaker 1>light's direction. This happens because the distances between some atoms

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<v Speaker 1>and the ice is molecular structure are close to the

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<v Speaker 1>height of light wavelengths, which means the light photons will

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<v Speaker 1>interact with those structures. The result is that the light

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<v Speaker 1>photons path is altered and it exits the ice in

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<v Speaker 1>a different direction than it entered The ice. Snow is

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<v Speaker 1>a whole bunch of individual ice crystals arranged together. When

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<v Speaker 1>a light photon enters a layer of snow, it goes

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<v Speaker 1>through an ice crystal on the top, which changes its

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<v Speaker 1>directions slightly and sends it onto a new ice crystal,

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<v Speaker 1>which does the same thing. Basically, all of those crystals

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<v Speaker 1>bounced the light all around so that it comes right

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<v Speaker 1>back out of the snow pile. It does the same

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<v Speaker 1>thing to all of the different light frequencies, so all

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<v Speaker 1>colors of light are bounced back out. The color of

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<v Speaker 1>all the frequencies in the visible spectrum combined in equal measure,

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<v Speaker 1>is white. So this is the color that we see

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<v Speaker 1>in snow, while it's not the color that we see

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<v Speaker 1>in the individual ice crystals from that snow. Today's episode

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<v Speaker 1>was written by Alice in mould Our Milk and produced

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<v Speaker 1>by Tyler Clang. For more on this and lots of

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<v Speaker 1>other colorful topics, visit how stuff works dot com. Brain

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<v Speaker 1>Stuff is production of iHeart Radio or more podcasts My

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