1 00:00:01,920 --> 00:00:04,320 Speaker 1: Welcome to brain Stuff, a production of I Heart Radio, 2 00:00:06,200 --> 00:00:09,920 Speaker 1: Hey brain Stuff, Lauren Bogle bomb here. One of the 3 00:00:10,000 --> 00:00:13,240 Speaker 1: reasons that people love snow is that it coats everything 4 00:00:13,320 --> 00:00:17,440 Speaker 1: in a blanket of dazzling white weather. Reporters will say 5 00:00:17,480 --> 00:00:19,480 Speaker 1: that we might be getting some of the white stuff, 6 00:00:19,760 --> 00:00:22,439 Speaker 1: and every December you're likely to hear the song White 7 00:00:22,520 --> 00:00:27,120 Speaker 1: Christmas over and over again. But if you think about it, 8 00:00:27,120 --> 00:00:29,880 Speaker 1: it seems weird that snow is white at all, since 9 00:00:29,920 --> 00:00:33,080 Speaker 1: it's just a bunch of ice crystals stuck together. So 10 00:00:33,280 --> 00:00:38,200 Speaker 1: where does it get its distinctive color. To understand where 11 00:00:38,240 --> 00:00:40,919 Speaker 1: this whiteness comes from, we need to back up and 12 00:00:40,960 --> 00:00:43,440 Speaker 1: look at why different things have different colors. In the 13 00:00:43,479 --> 00:00:46,720 Speaker 1: first place, visible light is made up of many different 14 00:00:46,760 --> 00:00:51,320 Speaker 1: frequencies of light. Our eyes detect different frequencies as different colors, 15 00:00:51,720 --> 00:00:55,040 Speaker 1: and different objects have different colors because the particles that 16 00:00:55,120 --> 00:00:59,040 Speaker 1: make up the object, it's atoms and molecules, react differently 17 00:00:59,080 --> 00:01:02,920 Speaker 1: to different frequencies or colors of light. The molecules and 18 00:01:02,960 --> 00:01:06,160 Speaker 1: atoms absorb a certain amount of light energy depending on 19 00:01:06,200 --> 00:01:09,000 Speaker 1: the frequency of the light, and then emit this absorbed 20 00:01:09,080 --> 00:01:12,960 Speaker 1: energy as heat. This means that any given object absorbs 21 00:01:13,040 --> 00:01:17,680 Speaker 1: certain frequencies of light more than other frequencies. A couple 22 00:01:17,680 --> 00:01:20,080 Speaker 1: of different things can happen to the light frequencies that 23 00:01:20,160 --> 00:01:23,959 Speaker 1: are not absorbed in some material. When a particle re 24 00:01:24,040 --> 00:01:27,560 Speaker 1: emits the photons, they continue to pass through to the 25 00:01:27,600 --> 00:01:30,959 Speaker 1: next particle. In this case, light travels all the way 26 00:01:30,959 --> 00:01:34,080 Speaker 1: through the material, which means the material will appear to 27 00:01:34,120 --> 00:01:38,600 Speaker 1: be clear, like a flat piece of glass. However, in 28 00:01:38,680 --> 00:01:41,760 Speaker 1: most solid materials, the particles re emit most of the 29 00:01:41,800 --> 00:01:45,320 Speaker 1: unabsorbed photons back out of the material, so that no 30 00:01:45,520 --> 00:01:49,400 Speaker 1: light or very little light passes through and the object 31 00:01:49,400 --> 00:01:53,200 Speaker 1: appears opaque. The color of an opaque object is just 32 00:01:53,320 --> 00:01:56,600 Speaker 1: the combination of the light frequencies that the objects particles 33 00:01:56,720 --> 00:01:59,800 Speaker 1: did not absorb, though the re emitted light can be 34 00:01:59,880 --> 00:02:03,640 Speaker 1: to stored it on the way out, and that is 35 00:02:03,680 --> 00:02:08,320 Speaker 1: why although ice is mostly clear, snow is mostly white. 36 00:02:09,200 --> 00:02:11,640 Speaker 1: Let's back up again and look at an individual piece 37 00:02:11,680 --> 00:02:16,919 Speaker 1: of ice. Ice is not transparent. It's actually translucent. This 38 00:02:17,000 --> 00:02:19,840 Speaker 1: means that the light photons don't pass right through the 39 00:02:19,919 --> 00:02:23,880 Speaker 1: material and a direct path the materials particles change the 40 00:02:23,960 --> 00:02:28,800 Speaker 1: light's direction. This happens because the distances between some atoms 41 00:02:28,840 --> 00:02:31,760 Speaker 1: and the ice is molecular structure are close to the 42 00:02:31,760 --> 00:02:35,359 Speaker 1: height of light wavelengths, which means the light photons will 43 00:02:35,400 --> 00:02:39,000 Speaker 1: interact with those structures. The result is that the light 44 00:02:39,040 --> 00:02:42,320 Speaker 1: photons path is altered and it exits the ice in 45 00:02:42,320 --> 00:02:46,560 Speaker 1: a different direction than it entered The ice. Snow is 46 00:02:46,600 --> 00:02:50,160 Speaker 1: a whole bunch of individual ice crystals arranged together. When 47 00:02:50,160 --> 00:02:52,840 Speaker 1: a light photon enters a layer of snow, it goes 48 00:02:52,880 --> 00:02:55,520 Speaker 1: through an ice crystal on the top, which changes its 49 00:02:55,560 --> 00:02:58,400 Speaker 1: directions slightly and sends it onto a new ice crystal, 50 00:02:58,520 --> 00:03:02,280 Speaker 1: which does the same thing. Basically, all of those crystals 51 00:03:02,280 --> 00:03:04,880 Speaker 1: bounced the light all around so that it comes right 52 00:03:04,919 --> 00:03:07,800 Speaker 1: back out of the snow pile. It does the same 53 00:03:07,840 --> 00:03:11,079 Speaker 1: thing to all of the different light frequencies, so all 54 00:03:11,160 --> 00:03:14,720 Speaker 1: colors of light are bounced back out. The color of 55 00:03:14,760 --> 00:03:18,200 Speaker 1: all the frequencies in the visible spectrum combined in equal measure, 56 00:03:18,680 --> 00:03:21,399 Speaker 1: is white. So this is the color that we see 57 00:03:21,400 --> 00:03:24,000 Speaker 1: in snow, while it's not the color that we see 58 00:03:24,040 --> 00:03:32,560 Speaker 1: in the individual ice crystals from that snow. Today's episode 59 00:03:32,560 --> 00:03:34,320 Speaker 1: was written by Alice in mould Our Milk and produced 60 00:03:34,320 --> 00:03:36,400 Speaker 1: by Tyler Clang. For more on this and lots of 61 00:03:36,440 --> 00:03:39,520 Speaker 1: other colorful topics, visit how stuff works dot com. Brain 62 00:03:39,560 --> 00:03:42,320 Speaker 1: Stuff is production of iHeart Radio or more podcasts My 63 00:03:42,400 --> 00:03:45,320 Speaker 1: heart Radio visit the iHeart Radio app, Apple Podcasts, or 64 00:03:45,360 --> 00:03:47,080 Speaker 1: wherever you listen to your favorite shows.