Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey, Brainstuff, learn
Speaker 1: voel bomb here. You may have noticed that whatever color
Speaker 1: a mountain range may be up close, a verdant green
Speaker 1: with foliage perhaps, or rusty clay red or capped with
Speaker 1: cold white snow. From a distance, they all tend to
Speaker 1: look blue. Australia's Blue Mountains and the Blue Ridge Mountains
Speaker 1: of the Eastern United States weren't named at random. After all.
Speaker 1: The beer brand COR's Light even used this science fact
Speaker 1: as a gimmick using cans printed with temperature sensitive ink.
Speaker 1: The little mountain peak in their logo turned from white
Speaker 1: to blue when the package hit what the brand purports
Speaker 1: to be the appropriate drinking temperature, that is, right around
Speaker 1: forty eight degrees fahrenheit or eight point eight degrees celsius
Speaker 1: or colder. But why blue? Oh, why not pink or
Speaker 1: yellow or verdant green? On a clear day, it can
Speaker 1: be hard to tell where some far flung mountain peaks
Speaker 1: and where the blue sky begins. The sky itself usually
Speaker 1: appears blue during the day thanks to atmospheric distortion and
Speaker 1: the limits of human eyesight. It's a phenomenon called Rayleigh scattering.
Speaker 1: Our sun the magnificent star upon which we all depend,
Speaker 1: gives off electromagnetic waves across the entire visible spectrum and
Speaker 1: a bit beyond it too. A sunlight usually appears white
Speaker 1: or eyes because it's a mix of all of the
Speaker 1: colors of the visible rainbow. We're talking red, orange, yellow, green, blue, indigo,
Speaker 1: and violet. But all of those colors of light have
Speaker 1: their own distinct wavelengths. A red light has the longest
Speaker 1: wavelength among them, a violet has the shortest. The colors
Speaker 1: all have their own amount of energy too. A red
Speaker 1: light is relatively sluggish, while milet light is relatively zippy.
Speaker 1: A sunlight requires an average of eight minutes and twenty
Speaker 1: seconds to reach the Earth. Things get interesting once it
Speaker 1: hits our atmosphere, which is loaded with unimaginably small air molecules.
Speaker 1: Even wavelengths of visible light, which are only about four
Speaker 1: hundred to seven hundred nanometers wide, absolutely tower over the
Speaker 1: tiny air molecules, which are less than a single nanometer each,
Speaker 1: But the size and energy of each particular wavelength of
Speaker 1: light matters. Zippier light with shorter wavelengths is more likely
Speaker 1: to hit those air molecules and get scattered around by them,
Speaker 1: bouncing like pingpong balls from one molecule to the next
Speaker 1: until it eventually hits our eyes from any number of
Speaker 1: possible directions, And wouldn't you know it. Blue light has
Speaker 1: one of the shortest wavelengths in the entire visible light spectrum,
Speaker 1: which means that blue colors scatter most in the atmosphere.
Speaker 1: It is true that violet wavelengths are even shorter, but
Speaker 1: the Sun releases less violet light than blue light to
Speaker 1: begin with, and human eyes detect blue more easily. This
Speaker 1: scattering of so much blue light in the atmosphere, combined
Speaker 1: with unequal blue light output from the Sun and the
Speaker 1: biases of our own vision, answers that age old question
Speaker 1: why is the sky blue? And we have this same
Speaker 1: process to thank for the bluish tint of distant mountains.
Speaker 1: When you gaze at a faraway summit, there's a whole
Speaker 1: lot of atmosphere sitting between your eyeballs and the actual mountain.
Speaker 1: The quantity will only increase with distance. A more air
Speaker 1: means more air molecules, which means more light scattering. As
Speaker 1: the space between you and your favorite mountain widens, the
Speaker 1: mountain appears bluer and fainter until finally it disappears from sight.
Speaker 1: That's why when we look at mountains far off in
Speaker 1: the distance, they appear blue. However, other things in the
Speaker 1: atmosphere can affect the way that we interpret a mountain's color.
Speaker 1: A dust and pollution can cause yellowish hazes, and compounds
Speaker 1: released by the vegetation adorning the aforementioned Blue Ridge Mountains,
Speaker 1: which extend from Georgia, Pennsylvania, help produce that iconic bluish haze.
Speaker 1: Today's episode is based on the article why distant mountains
Speaker 1: appear blue to the Naked eye on how stuffworks dot Com,
Speaker 1: written by Mark Mancini. Brain Stuff is production of iHeartRadio
Speaker 1: in partnership with HowStuffWorks dot Com and is produced by
Speaker 1: Tyler Klang. Four more podcasts from my heart Radio, visit
Speaker 1: the iHeartRadio app, Apple Podcasts, or wherever you listen to
Speaker 1: your favorite shows.