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Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff

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Speaker 1: Lauren vogelbaumb Here, someone gazing out at the ocean from

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Speaker 1: the coast of Maine might see deep, navy to midnight

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Speaker 1: blue water, very different hues than someone squinting at the

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Speaker 1: bright turquoise sea from a sunny beach on a Greek island.

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Speaker 1: So why is the ocean blue? And why does it

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Speaker 1: come in so many different shades? Before the article this

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Speaker 1: episode is based on how Stuff Work, spoke with NASA

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Speaker 1: oceanographer Jean Carl Feldman, who pointed out that, first of all, quote,

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Speaker 1: the water of the ocean is not blue, it's clear.

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Speaker 1: The color of the ocean's surface, for the most part,

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Speaker 1: is based on depth, what's in it and what's below it.

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Speaker 1: That's right. All water is clear by its nature. But

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Speaker 1: here's why it looks different in a glass versus from

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Speaker 1: a beach. A glass of water appears clear because light

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Speaker 1: passes through it with little to no obstruction. But if

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Speaker 1: a body of water is deep enough that light isn't

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Speaker 1: reflected off the bottom, it appears blue. Basic physics explains

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Speaker 1: why a visible light is made up of a spectrum

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Speaker 1: of different wavelengths The longer wavelengths appear to our eyes

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Speaker 1: as shades of red and orange, while the shorter ones

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Speaker 1: appear as blues and violets. When light strikes the ocean,

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Speaker 1: it interacts with water molecules and can be either absorbed

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Speaker 1: or scattered. If nothing is in the water except water molecules,

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Speaker 1: the longer red portions of the spectrum are absorbed by

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Speaker 1: the water. The shorter, zippier blue wavelengths are more likely

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Speaker 1: to hit something, including water and scatter, meaning they make

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Speaker 1: it back to our eyes, meaning the ocean appears blue.

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Speaker 1: Violet wavelengths are even shorter in zippier, but there are

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Speaker 1: fewer of them in sunlight, and our eyes perceive the

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Speaker 1: blue ones better at long distances, like near the horizon.

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Speaker 1: Another factor that we've actually talked about in a different

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Speaker 1: episode comes into play. A mountains appear blue in the

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Speaker 1: distance no matter what color they are up close, because

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Speaker 1: the air itself is made up of molecules that scatter

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Speaker 1: those zippy blue wavelengths of light, so the ocean far

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Speaker 1: out in the distance may look bluer than the water

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Speaker 1: near a beach. The depth of the water and what

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Speaker 1: the ocean floor is made of also influence this, A

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Speaker 1: Feldman explained in Grease, the water is this beautiful turquoise

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Speaker 1: color because the bottom is either white sand or white rocks.

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Speaker 1: What's happening here is that the light hits the shallow

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Speaker 1: sea floor and then bounces back up, projecting the beautiful

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Speaker 1: blue green color you see in the water. It's particularly

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Speaker 1: bright because some of those beaches have very little stuff

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Speaker 1: in the water, but the ocean is often teeming with

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Speaker 1: tiny planted animal life or fulfilled with suspended sediment or containinents.

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Speaker 1: Oceanographers monitor the ocean color as doctors read the vital

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Speaker 1: signs of their patients. The color seen on the ocean's

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Speaker 1: surface reflects what's going on in its vast depths pun intended.

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Speaker 1: A Feldman, who is based at the NASA Goddard Space

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Speaker 1: Flight Center in Maryland, studies images taken by the Sea

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Speaker 1: Viewing Wide Field of View Sensor satellite, which launched back

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Speaker 1: in nineteen ninety seven. From its orbit more than four

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Speaker 1: hundred miles or six hundred and fifty kilometers above Earth,

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Speaker 1: the satellite captures van go like swirls of the ocean's colors.

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Speaker 1: The patterns are not only mesmerizing, but they also show

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Speaker 1: where sediment and runoff may make the water appure a

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Speaker 1: muddy brown color, or where microscopic plants called phytoplankton collected

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Speaker 1: nutrient rich waters and tinting it green. Phytoplankton use chlorophyll,

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Speaker 1: which is a green pigment, to capture energy from the

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Speaker 1: sun to convert water in carbon dioxide into food to

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Speaker 1: fuel themselves. Through this process called photosynthesis, phytoplankton generate about

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Speaker 1: half of the oxygen we breathe. While most phytoplankton give

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Speaker 1: ocean water a green tint, some lend it a yellow, reddish,

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Speaker 1: or brown tint. Oceans with high concentrations of phytoplankton can

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Speaker 1: appear blue green to green, depending on the density. Greenish

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Speaker 1: water may not sound appealing, but as Feldman says, if

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Speaker 1: it weren't for phytoplankton, we wouldn't be here. Phytoplanktons serve

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Speaker 1: as the base of the ocean's food web because they're

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Speaker 1: the primary source of food for zooplankton, which are tiny

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Speaker 1: animals that are eaten by fish. The fish are then

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Speaker 1: eaten by bigger animals like whales and sharks. But when

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Speaker 1: oceans become polluted with runoff, the amount of phytoplankton can

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Speaker 1: escalate to unhealthy levels. Phytoplankton feed on the pollutants, flourish

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Speaker 1: and then die in huge numbers, sinking to the bottom

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Speaker 1: and decomposing in a process that depletes oxygen from the water,

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Speaker 1: which means larger animals can't survive there. On a map

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Speaker 1: on Feldman's office wall is a mark showing a spot

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Speaker 1: where there is little human interference and the ocean water

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Speaker 1: is perhaps the clearest and cleanest on the planet. In

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Speaker 1: this region, off the coast of Easter Island in the

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Speaker 1: Southeast Pacific Ocean, the water is deep and remarkably clear

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Speaker 1: due to its location in the middle of a giant

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Speaker 1: oceanic guyer a large circular current. Its central location means

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Speaker 1: there's minimal mixing of ocean layers, and sediment isn't pushed

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Speaker 1: up from the deep bottom. The purity of the water here,

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Speaker 1: coupled with its depth, make the ocean here appear a

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Speaker 1: deeper indigo than perhaps anywhere else. Feldman said, the light

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Speaker 1: just keeps going down, down, down, There's nothing that bounces aback.

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Speaker 1: Here is the deepest blue you'll ever see. That being said,

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Speaker 1: of course, light doesn't just keep going down into the

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Speaker 1: water forever. Eventually the water absorbs all of it and

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Speaker 1: nothing is left to bounce back up to the surface.

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Speaker 1: Band our eyes. Over half of all visible light is

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Speaker 1: absorbed within the first ten meters or thirty feet of

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Speaker 1: water at the ocean's surface. At one hundred meters or

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Speaker 1: three hundred feet, ninety nine percent of light will have

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Speaker 1: been absorbed. Even in very clear water. That's where you

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Speaker 1: get that deep indigo off Easter Island. All of the longer,

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Speaker 1: slower wavelengths have been absorbed, leaving only the darkest violet blue. However,

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Speaker 1: at about twice that depth, light never penetrates, and everything

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Speaker 1: that lives there lives in total darkness unless they create

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Speaker 1: their own light through by aluminescence. But that's a different episode.

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Speaker 1: Today's episode is based on the article why is the

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Speaker 1: ocean different colors in different places? On HowStuffWorks dot Com?

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Speaker 1: Written by Amanda Onion. Rain Stuff is production by Heart

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Speaker 1: Radio in partnership with how Stuffworks dot Com and is

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Speaker 1: produced by Tyler Klang. Four more podcasts fy Heart Radio,

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Speaker 1: visit the iHeartRadio app, Apple podcast Guests, or wherever you

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Speaker 1: listen to your favorite shows