WEBVTT - Why Do Distant Mountains Appear Blue?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio. Hey, Brainstuff, learn

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<v Speaker 1>voel bomb here. You may have noticed that whatever color

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<v Speaker 1>a mountain range may be up close, a verdant green

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<v Speaker 1>with foliage perhaps, or rusty clay red or capped with

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<v Speaker 1>cold white snow. From a distance, they all tend to

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<v Speaker 1>look blue. Australia's Blue Mountains and the Blue Ridge Mountains

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<v Speaker 1>of the Eastern United States weren't named at random. After all.

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<v Speaker 1>The beer brand COR's Light even used this science fact

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<v Speaker 1>as a gimmick using cans printed with temperature sensitive ink.

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<v Speaker 1>The little mountain peak in their logo turned from white

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<v Speaker 1>to blue when the package hit what the brand purports

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<v Speaker 1>to be the appropriate drinking temperature, that is, right around

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<v Speaker 1>forty eight degrees fahrenheit or eight point eight degrees celsius

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<v Speaker 1>or colder. But why blue? Oh, why not pink or

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<v Speaker 1>yellow or verdant green? On a clear day, it can

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<v Speaker 1>be hard to tell where some far flung mountain peaks

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<v Speaker 1>and where the blue sky begins. The sky itself usually

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<v Speaker 1>appears blue during the day thanks to atmospheric distortion and

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<v Speaker 1>the limits of human eyesight. It's a phenomenon called Rayleigh scattering.

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<v Speaker 1>Our sun the magnificent star upon which we all depend,

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<v Speaker 1>gives off electromagnetic waves across the entire visible spectrum and

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<v Speaker 1>a bit beyond it too. A sunlight usually appears white

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<v Speaker 1>or eyes because it's a mix of all of the

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<v Speaker 1>colors of the visible rainbow. We're talking red, orange, yellow, green, blue, indigo,

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<v Speaker 1>and violet. But all of those colors of light have

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<v Speaker 1>their own distinct wavelengths. A red light has the longest

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<v Speaker 1>wavelength among them, a violet has the shortest. The colors

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<v Speaker 1>all have their own amount of energy too. A red

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<v Speaker 1>light is relatively sluggish, while milet light is relatively zippy.

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<v Speaker 1>A sunlight requires an average of eight minutes and twenty

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<v Speaker 1>seconds to reach the Earth. Things get interesting once it

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<v Speaker 1>hits our atmosphere, which is loaded with unimaginably small air molecules.

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<v Speaker 1>Even wavelengths of visible light, which are only about four

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<v Speaker 1>hundred to seven hundred nanometers wide, absolutely tower over the

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<v Speaker 1>tiny air molecules, which are less than a single nanometer each,

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<v Speaker 1>But the size and energy of each particular wavelength of

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<v Speaker 1>light matters. Zippier light with shorter wavelengths is more likely

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<v Speaker 1>to hit those air molecules and get scattered around by them,

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<v Speaker 1>bouncing like pingpong balls from one molecule to the next

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<v Speaker 1>until it eventually hits our eyes from any number of

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<v Speaker 1>possible directions, And wouldn't you know it. Blue light has

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<v Speaker 1>one of the shortest wavelengths in the entire visible light spectrum,

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<v Speaker 1>which means that blue colors scatter most in the atmosphere.

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<v Speaker 1>It is true that violet wavelengths are even shorter, but

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<v Speaker 1>the Sun releases less violet light than blue light to

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<v Speaker 1>begin with, and human eyes detect blue more easily. This

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<v Speaker 1>scattering of so much blue light in the atmosphere, combined

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<v Speaker 1>with unequal blue light output from the Sun and the

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<v Speaker 1>biases of our own vision, answers that age old question

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<v Speaker 1>why is the sky blue? And we have this same

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<v Speaker 1>process to thank for the bluish tint of distant mountains.

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<v Speaker 1>When you gaze at a faraway summit, there's a whole

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<v Speaker 1>lot of atmosphere sitting between your eyeballs and the actual mountain.

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<v Speaker 1>The quantity will only increase with distance. A more air

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<v Speaker 1>means more air molecules, which means more light scattering. As

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<v Speaker 1>the space between you and your favorite mountain widens, the

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<v Speaker 1>mountain appears bluer and fainter until finally it disappears from sight.

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<v Speaker 1>That's why when we look at mountains far off in

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<v Speaker 1>the distance, they appear blue. However, other things in the

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<v Speaker 1>atmosphere can affect the way that we interpret a mountain's color.

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<v Speaker 1>A dust and pollution can cause yellowish hazes, and compounds

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<v Speaker 1>released by the vegetation adorning the aforementioned Blue Ridge Mountains,

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<v Speaker 1>which extend from Georgia, Pennsylvania, help produce that iconic bluish haze.

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<v Speaker 1>Today's episode is based on the article why distant mountains

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<v Speaker 1>appear blue to the Naked eye on how stuffworks dot Com,

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<v Speaker 1>written by Mark Mancini. Brain Stuff is production of iHeartRadio

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<v Speaker 1>in partnership with HowStuffWorks dot Com and is produced by

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<v Speaker 1>Tyler Klang. Four more podcasts from my heart Radio, visit

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<v Speaker 1>the iHeartRadio app, Apple Podcasts, or wherever you listen to

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<v Speaker 1>your favorite shows.