1 00:00:01,840 --> 00:00:07,880 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey, Brainstuff, learn 2 00:00:07,960 --> 00:00:13,040 Speaker 1: voel bomb here. You may have noticed that whatever color 3 00:00:13,119 --> 00:00:16,279 Speaker 1: a mountain range may be up close, a verdant green 4 00:00:16,280 --> 00:00:20,079 Speaker 1: with foliage perhaps, or rusty clay red or capped with 5 00:00:20,239 --> 00:00:24,000 Speaker 1: cold white snow. From a distance, they all tend to 6 00:00:24,000 --> 00:00:28,240 Speaker 1: look blue. Australia's Blue Mountains and the Blue Ridge Mountains 7 00:00:28,240 --> 00:00:31,280 Speaker 1: of the Eastern United States weren't named at random. After all. 8 00:00:33,080 --> 00:00:36,280 Speaker 1: The beer brand COR's Light even used this science fact 9 00:00:36,280 --> 00:00:39,800 Speaker 1: as a gimmick using cans printed with temperature sensitive ink. 10 00:00:40,240 --> 00:00:43,440 Speaker 1: The little mountain peak in their logo turned from white 11 00:00:43,440 --> 00:00:45,959 Speaker 1: to blue when the package hit what the brand purports 12 00:00:45,960 --> 00:00:49,000 Speaker 1: to be the appropriate drinking temperature, that is, right around 13 00:00:49,040 --> 00:00:52,320 Speaker 1: forty eight degrees fahrenheit or eight point eight degrees celsius 14 00:00:52,560 --> 00:00:58,320 Speaker 1: or colder. But why blue? Oh, why not pink or 15 00:00:58,520 --> 00:01:03,240 Speaker 1: yellow or verdant green? On a clear day, it can 16 00:01:03,280 --> 00:01:06,440 Speaker 1: be hard to tell where some far flung mountain peaks 17 00:01:06,480 --> 00:01:11,440 Speaker 1: and where the blue sky begins. The sky itself usually 18 00:01:11,480 --> 00:01:15,200 Speaker 1: appears blue during the day thanks to atmospheric distortion and 19 00:01:15,360 --> 00:01:19,920 Speaker 1: the limits of human eyesight. It's a phenomenon called Rayleigh scattering. 20 00:01:21,640 --> 00:01:25,160 Speaker 1: Our sun the magnificent star upon which we all depend, 21 00:01:25,680 --> 00:01:30,000 Speaker 1: gives off electromagnetic waves across the entire visible spectrum and 22 00:01:30,040 --> 00:01:34,119 Speaker 1: a bit beyond it too. A sunlight usually appears white 23 00:01:34,280 --> 00:01:36,319 Speaker 1: or eyes because it's a mix of all of the 24 00:01:36,360 --> 00:01:41,560 Speaker 1: colors of the visible rainbow. We're talking red, orange, yellow, green, blue, indigo, 25 00:01:41,640 --> 00:01:46,080 Speaker 1: and violet. But all of those colors of light have 26 00:01:46,200 --> 00:01:50,360 Speaker 1: their own distinct wavelengths. A red light has the longest 27 00:01:50,360 --> 00:01:54,400 Speaker 1: wavelength among them, a violet has the shortest. The colors 28 00:01:54,440 --> 00:01:57,680 Speaker 1: all have their own amount of energy too. A red 29 00:01:57,760 --> 00:02:01,760 Speaker 1: light is relatively sluggish, while milet light is relatively zippy. 30 00:02:03,360 --> 00:02:06,440 Speaker 1: A sunlight requires an average of eight minutes and twenty 31 00:02:06,440 --> 00:02:10,400 Speaker 1: seconds to reach the Earth. Things get interesting once it 32 00:02:10,480 --> 00:02:15,520 Speaker 1: hits our atmosphere, which is loaded with unimaginably small air molecules. 33 00:02:16,080 --> 00:02:19,119 Speaker 1: Even wavelengths of visible light, which are only about four 34 00:02:19,160 --> 00:02:23,560 Speaker 1: hundred to seven hundred nanometers wide, absolutely tower over the 35 00:02:23,680 --> 00:02:27,360 Speaker 1: tiny air molecules, which are less than a single nanometer each, 36 00:02:29,320 --> 00:02:32,960 Speaker 1: But the size and energy of each particular wavelength of 37 00:02:33,040 --> 00:02:37,480 Speaker 1: light matters. Zippier light with shorter wavelengths is more likely 38 00:02:37,560 --> 00:02:40,919 Speaker 1: to hit those air molecules and get scattered around by them, 39 00:02:41,240 --> 00:02:44,480 Speaker 1: bouncing like pingpong balls from one molecule to the next 40 00:02:44,840 --> 00:02:47,840 Speaker 1: until it eventually hits our eyes from any number of 41 00:02:47,919 --> 00:02:52,880 Speaker 1: possible directions, And wouldn't you know it. Blue light has 42 00:02:52,960 --> 00:02:56,600 Speaker 1: one of the shortest wavelengths in the entire visible light spectrum, 43 00:02:56,680 --> 00:03:00,000 Speaker 1: which means that blue colors scatter most in the atmosphere. 44 00:03:01,600 --> 00:03:04,640 Speaker 1: It is true that violet wavelengths are even shorter, but 45 00:03:04,800 --> 00:03:07,640 Speaker 1: the Sun releases less violet light than blue light to 46 00:03:07,680 --> 00:03:12,799 Speaker 1: begin with, and human eyes detect blue more easily. This 47 00:03:13,000 --> 00:03:16,640 Speaker 1: scattering of so much blue light in the atmosphere, combined 48 00:03:16,680 --> 00:03:19,480 Speaker 1: with unequal blue light output from the Sun and the 49 00:03:19,520 --> 00:03:23,040 Speaker 1: biases of our own vision, answers that age old question 50 00:03:23,600 --> 00:03:27,960 Speaker 1: why is the sky blue? And we have this same 51 00:03:28,040 --> 00:03:31,240 Speaker 1: process to thank for the bluish tint of distant mountains. 52 00:03:32,720 --> 00:03:35,720 Speaker 1: When you gaze at a faraway summit, there's a whole 53 00:03:35,800 --> 00:03:39,800 Speaker 1: lot of atmosphere sitting between your eyeballs and the actual mountain. 54 00:03:40,640 --> 00:03:44,720 Speaker 1: The quantity will only increase with distance. A more air 55 00:03:44,960 --> 00:03:50,560 Speaker 1: means more air molecules, which means more light scattering. As 56 00:03:50,600 --> 00:03:53,920 Speaker 1: the space between you and your favorite mountain widens, the 57 00:03:53,960 --> 00:03:59,080 Speaker 1: mountain appears bluer and fainter until finally it disappears from sight. 58 00:04:00,240 --> 00:04:02,280 Speaker 1: That's why when we look at mountains far off in 59 00:04:02,360 --> 00:04:07,200 Speaker 1: the distance, they appear blue. However, other things in the 60 00:04:07,240 --> 00:04:10,520 Speaker 1: atmosphere can affect the way that we interpret a mountain's color. 61 00:04:11,120 --> 00:04:15,640 Speaker 1: A dust and pollution can cause yellowish hazes, and compounds 62 00:04:15,680 --> 00:04:19,160 Speaker 1: released by the vegetation adorning the aforementioned Blue Ridge Mountains, 63 00:04:19,360 --> 00:04:25,680 Speaker 1: which extend from Georgia, Pennsylvania, help produce that iconic bluish haze. 64 00:04:29,400 --> 00:04:32,400 Speaker 1: Today's episode is based on the article why distant mountains 65 00:04:32,400 --> 00:04:35,080 Speaker 1: appear blue to the Naked eye on how stuffworks dot Com, 66 00:04:35,120 --> 00:04:38,520 Speaker 1: written by Mark Mancini. Brain Stuff is production of iHeartRadio 67 00:04:38,600 --> 00:04:41,080 Speaker 1: in partnership with HowStuffWorks dot Com and is produced by 68 00:04:41,120 --> 00:04:44,520 Speaker 1: Tyler Klang. Four more podcasts from my heart Radio, visit 69 00:04:44,520 --> 00:04:47,560 Speaker 1: the iHeartRadio app, Apple Podcasts, or wherever you listen to 70 00:04:47,600 --> 00:04:58,040 Speaker 1: your favorite shows.