Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff Lauren vogelbaumb Here, someone gazing out at the ocean from the coast of Maine might see deep, navy to midnight blue water, very different hues than someone squinting at the bright turquoise sea from a sunny beach on a Greek island. So why is the ocean blue? And why does it
come in so many different shades? Before the article this episode is based on how Stuff Work, spoke with NASA oceanographer Jean Carl Feldman, who pointed out that, first of all, quote, the water of the ocean is not blue, it's clear. The color of the ocean's surface, for the most part, is based on depth, what's in it and what's below it. That's right. All water is clear by its nature. But here's why it looks different in a glass versus from a beach. A glass of water appears clear because light
passes through it with little to no obstruction. But if a body of water is deep enough that light isn't reflected off the bottom, it appears blue. Basic physics explains why a visible light is made up of a spectrum of different wavelengths The longer wavelengths appear to our eyes as shades of red and orange, while the shorter ones appear as blues and violets. When light strikes the ocean, it interacts with water molecules and can be either absorbed
or scattered. If nothing is in the water except water molecules, the longer red portions of the spectrum are absorbed by the water. The shorter, zippier blue wavelengths are more likely to hit something, including water and scatter, meaning they make it back to our eyes, meaning the ocean appears blue. Violet wavelengths are even shorter in zippier, but there are fewer of them in sunlight, and our eyes perceive the blue ones better at long distances, like near the horizon.
Another factor that we've actually talked about in a different episode comes into play. A mountains appear blue in the distance no matter what color they are up close, because the air itself is made up of molecules that scatter those zippy blue wavelengths of light, so the ocean far out in the distance may look bluer than the water
near a beach. The depth of the water and what the ocean floor is made of also influence this, A Feldman explained in Grease, the water is this beautiful turquoise color because the bottom is either white sand or white rocks. What's happening here is that the light hits the shallow sea floor and then bounces back up, projecting the beautiful
blue green color you see in the water. It's particularly bright because some of those beaches have very little stuff in the water, but the ocean is often teeming with tiny planted animal life or fulfilled with suspended sediment or containinents. Oceanographers monitor the ocean color as doctors read the vital signs of their patients. The color seen on the ocean's surface reflects what's going on in its vast depths pun intended.
A Feldman, who is based at the NASA Goddard Space Flight Center in Maryland, studies images taken by the Sea Viewing Wide Field of View Sensor satellite, which launched back in nineteen ninety seven. From its orbit more than four hundred miles or six hundred and fifty kilometers above Earth, the satellite captures van go like swirls of the ocean's colors.
The patterns are not only mesmerizing, but they also show where sediment and runoff may make the water appure a muddy brown color, or where microscopic plants called phytoplankton collected nutrient rich waters and tinting it green. Phytoplankton use chlorophyll, which is a green pigment, to capture energy from the sun to convert water in carbon dioxide into food to fuel themselves. Through this process called photosynthesis, phytoplankton generate about
half of the oxygen we breathe. While most phytoplankton give ocean water a green tint, some lend it a yellow, reddish, or brown tint. Oceans with high concentrations of phytoplankton can appear blue green to green, depending on the density. Greenish water may not sound appealing, but as Feldman says, if it weren't for phytoplankton, we wouldn't be here. Phytoplanktons serve as the base of the ocean's food web because they're the primary source of food for zooplankton, which are tiny
animals that are eaten by fish. The fish are then eaten by bigger animals like whales and sharks. But when oceans become polluted with runoff, the amount of phytoplankton can escalate to unhealthy levels. Phytoplankton feed on the pollutants, flourish and then die in huge numbers, sinking to the bottom and decomposing in a process that depletes oxygen from the water,
which means larger animals can't survive there. On a map on Feldman's office wall is a mark showing a spot where there is little human interference and the ocean water is perhaps the clearest and cleanest on the planet. In this region, off the coast of Easter Island in the Southeast Pacific Ocean, the water is deep and remarkably clear due to its location in the middle of a giant
oceanic guyer a large circular current. Its central location means there's minimal mixing of ocean layers, and sediment isn't pushed up from the deep bottom. The purity of the water here, coupled with its depth, make the ocean here appear a deeper indigo than perhaps anywhere else. Feldman said, the light just keeps going down, down, down, There's nothing that bounces aback. Here is the deepest blue you'll ever see. That being said, of course, light doesn't just keep going down into the
water forever. Eventually the water absorbs all of it and nothing is left to bounce back up to the surface. Band our eyes. Over half of all visible light is absorbed within the first ten meters or thirty feet of water at the ocean's surface. At one hundred meters or three hundred feet, ninety nine percent of light will have been absorbed. Even in very clear water. That's where you get that deep indigo off Easter Island. All of the longer,
slower wavelengths have been absorbed, leaving only the darkest violet blue. However, at about twice that depth, light never penetrates, and everything that lives there lives in total darkness unless they create their own light through by aluminescence. But that's a different episode. Today's episode is based on the article why is the ocean different colors in different places? On HowStuffWorks dot Com?
Written by Amanda Onion. Rain Stuff is production by Heart Radio in partnership with how Stuffworks dot Com and is produced by Tyler Klang. Four more podcasts fy Heart Radio, visit the iHeartRadio app, Apple podcast Guests, or wherever you listen to your favorite shows