1 00:00:01,920 --> 00:00:07,160 Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff, 2 00:00:07,200 --> 00:00:10,879 Speaker 1: Lauren Vogal Bomb. Here, someone gazing out at the ocean 3 00:00:10,920 --> 00:00:14,160 Speaker 1: from the main coast sees very different hues than someone 4 00:00:14,240 --> 00:00:16,079 Speaker 1: squinting at the sea from a sunny beach on a 5 00:00:16,120 --> 00:00:19,160 Speaker 1: Greek island. But why does the ocean come in so 6 00:00:19,200 --> 00:00:23,640 Speaker 1: many shades of blue? Of course, ocean water isn't inherently blue. 7 00:00:23,680 --> 00:00:26,280 Speaker 1: It's clear the colors that we see on the surface 8 00:00:26,320 --> 00:00:28,920 Speaker 1: are the result of light being absorbed and reflected by 9 00:00:28,960 --> 00:00:31,400 Speaker 1: the water itself, whatever is floating and living in it, 10 00:00:31,560 --> 00:00:35,199 Speaker 1: and the surface of the ocean floor below it. A 11 00:00:35,240 --> 00:00:37,960 Speaker 1: glass of water will of course appear clear as visible 12 00:00:38,000 --> 00:00:41,000 Speaker 1: light passes through it with little to no obstruction. But 13 00:00:41,120 --> 00:00:43,080 Speaker 1: if a body of water is deep enough that light 14 00:00:43,159 --> 00:00:47,680 Speaker 1: isn't reflected off the bottom, it appears blue. Basic physics 15 00:00:47,680 --> 00:00:50,640 Speaker 1: explains why light from the sun is made up of 16 00:00:50,640 --> 00:00:54,120 Speaker 1: a spectrum of different wavelengths. The longer wavelengths appear to 17 00:00:54,120 --> 00:00:56,720 Speaker 1: our eyes as the reds and oranges, while the shorter 18 00:00:56,800 --> 00:01:00,960 Speaker 1: ones appear blue and green. When the Sun's strikes the ocean, 19 00:01:01,200 --> 00:01:04,280 Speaker 1: it interacts with water molecules and can be either absorbed 20 00:01:04,400 --> 00:01:07,800 Speaker 1: or scattered. If nothing is in the water except water. 21 00:01:08,240 --> 00:01:10,679 Speaker 1: The longer red portions of the spectrum tend to be 22 00:01:10,720 --> 00:01:14,120 Speaker 1: absorbed by the water molecules, whereas the light of those 23 00:01:14,120 --> 00:01:17,119 Speaker 1: shorter wavelengths is more likely to go deep, hit water 24 00:01:17,160 --> 00:01:20,360 Speaker 1: molecules there, and scatter back up towards our eyes, making 25 00:01:20,360 --> 00:01:24,920 Speaker 1: the ocean appear blue. Depth and the ocean bottom also 26 00:01:24,959 --> 00:01:27,720 Speaker 1: influence whether the surface appears a dusky dark blue, as 27 00:01:27,760 --> 00:01:30,759 Speaker 1: in parts of the Atlantic, or casts a sapphire like shiver, 28 00:01:30,920 --> 00:01:35,119 Speaker 1: as in many tropical locations. We spoke with NASA oceanographer 29 00:01:35,319 --> 00:01:39,480 Speaker 1: Jeane carl Feldman. He said, in Greece, the water is 30 00:01:39,520 --> 00:01:42,360 Speaker 1: this beautiful turquoise color because the bottom is either white 31 00:01:42,360 --> 00:01:46,039 Speaker 1: sand or white rocks. What happens is the light comes 32 00:01:46,080 --> 00:01:48,720 Speaker 1: down and blue light gets down, hits the bottom, and 33 00:01:48,720 --> 00:01:51,480 Speaker 1: then reflects back up, So you make this beautiful light 34 00:01:51,520 --> 00:01:55,640 Speaker 1: blue color in the water. Darker sand rocks or other 35 00:01:55,680 --> 00:02:00,760 Speaker 1: formations mean darker water. The color is further complicated by 36 00:02:00,800 --> 00:02:03,120 Speaker 1: the fact that the ocean is rarely just water, but 37 00:02:03,280 --> 00:02:06,240 Speaker 1: is instead teeming with tiny plant and animal life, plus 38 00:02:06,320 --> 00:02:11,280 Speaker 1: suspended sediment or other natural or band made contaminants. Oceanographers 39 00:02:11,280 --> 00:02:13,960 Speaker 1: monitor the ocean's color the way that doctors read vital 40 00:02:14,000 --> 00:02:17,200 Speaker 1: signs of their patients. Colors seen on the ocean's surface 41 00:02:17,360 --> 00:02:22,320 Speaker 1: reflect what's going on in its vast depths. Feldman, who 42 00:02:22,400 --> 00:02:25,040 Speaker 1: is based at the NASA Goddard Space Flight Center in Maryland, 43 00:02:25,240 --> 00:02:28,440 Speaker 1: studies images taken by the sea viewing wide field of 44 00:02:28,520 --> 00:02:33,120 Speaker 1: view since her satellite launched in from its perch more 45 00:02:33,160 --> 00:02:35,760 Speaker 1: than four hundred miles above Earth or nearly six hundred 46 00:02:35,840 --> 00:02:39,359 Speaker 1: fifty kilometers, The satellite captures van go like swirls with 47 00:02:39,400 --> 00:02:43,120 Speaker 1: the ocean's colors. The patterns are not only mesmerizing, but 48 00:02:43,160 --> 00:02:45,920 Speaker 1: they also reflect where sediment and runoff may make water 49 00:02:46,000 --> 00:02:49,840 Speaker 1: appear a dull brown, and where microscopic plants called phytoplankton 50 00:02:50,000 --> 00:02:55,119 Speaker 1: collect in nutrient rich waters, often tinting it green. Phytoplankton 51 00:02:55,240 --> 00:02:58,160 Speaker 1: used chlorophyll to capture energy from the sun to convert 52 00:02:58,240 --> 00:03:02,560 Speaker 1: water and carbon dioxide into energy and then waste. Through 53 00:03:02,560 --> 00:03:06,360 Speaker 1: this process called photosynthesis, phytoplankton generate about half of the 54 00:03:06,400 --> 00:03:11,360 Speaker 1: oxygen we breathe. Oceans with high concentrations of phytoplankton can 55 00:03:11,400 --> 00:03:14,560 Speaker 1: appear blue green to green, depending on the density. Some 56 00:03:14,680 --> 00:03:18,480 Speaker 1: lend the water a yellow, reddish or brown tint. Phytoplankton 57 00:03:18,600 --> 00:03:21,079 Speaker 1: serve as the base of the food web and primary 58 00:03:21,080 --> 00:03:24,120 Speaker 1: source of food for zooplankton, which are tiny animals eaten 59 00:03:24,120 --> 00:03:26,720 Speaker 1: by fish. The fish are then eaten by bigger animals 60 00:03:26,760 --> 00:03:31,200 Speaker 1: like whales and sharks. It's when oceans become polluted with 61 00:03:31,280 --> 00:03:34,760 Speaker 1: runoff that the amount of phytoplankton can escalate to unhealthy levels. 62 00:03:35,400 --> 00:03:39,240 Speaker 1: Phytoplankton feed on the pollutants, flourish, and then die, sinking 63 00:03:39,240 --> 00:03:41,640 Speaker 1: to the bottom to decompose in a process that depletes 64 00:03:41,680 --> 00:03:46,040 Speaker 1: oxygen from the water. Over the past fifty years, ocean 65 00:03:46,160 --> 00:03:49,160 Speaker 1: zones with depleted oxygen have more than quadrupled to an 66 00:03:49,200 --> 00:03:52,480 Speaker 1: area roughly the size of the European Union. Part of 67 00:03:52,520 --> 00:03:54,960 Speaker 1: the cause may be an increase in ocean temperature due 68 00:03:55,000 --> 00:03:59,680 Speaker 1: to climate change, since warmer water supports less oxygen. In 69 00:04:00,040 --> 00:04:03,000 Speaker 1: still areas, phytoplankton blooms are suspected to be the cause. 70 00:04:04,000 --> 00:04:06,520 Speaker 1: Phytoplankton may serve as the base of the ocean food chain, 71 00:04:06,760 --> 00:04:08,880 Speaker 1: but as Feldman says, too much of a good thing 72 00:04:09,040 --> 00:04:12,120 Speaker 1: is not a good thing. On a map on Feldman's 73 00:04:12,120 --> 00:04:14,720 Speaker 1: office wall is a marker showing where there's little human 74 00:04:14,760 --> 00:04:18,080 Speaker 1: interference and ocean water is perhaps the clearest on the planet. 75 00:04:18,839 --> 00:04:20,919 Speaker 1: In this region, off the coast of Eastern Island in 76 00:04:20,920 --> 00:04:24,240 Speaker 1: the Southeast Pacific Ocean. The water is deep and remarkably 77 00:04:24,279 --> 00:04:26,120 Speaker 1: clear due to its location in the middle of a 78 00:04:26,160 --> 00:04:30,159 Speaker 1: giant oceanic eye, which is a large circular current. Its 79 00:04:30,160 --> 00:04:33,479 Speaker 1: central location means there's minimal mixing of ocean layers and 80 00:04:33,560 --> 00:04:36,880 Speaker 1: nutrients aren't pushed up from the deep bottom. The purity 81 00:04:36,920 --> 00:04:39,039 Speaker 1: of the water they're coupled with the depth make the 82 00:04:39,080 --> 00:04:43,960 Speaker 1: ocean appear a deeper indigo than perhaps anywhere else. Feldman said, 83 00:04:44,320 --> 00:04:47,720 Speaker 1: the light just keeps going down, down, down. There's nothing 84 00:04:47,720 --> 00:04:50,800 Speaker 1: that bounces it back. Here is the deepest blue you'll 85 00:04:50,839 --> 00:04:59,080 Speaker 1: ever see. Today's episode writtain by Amanda Onion and produced 86 00:04:59,080 --> 00:05:01,479 Speaker 1: by Tyler Clang. Brain Stuff is a production of I 87 00:05:01,560 --> 00:05:03,640 Speaker 1: Heart Radio's How Stuff Works. For more in this and 88 00:05:03,720 --> 00:05:05,800 Speaker 1: lots of other topics is our Home Planet has to 89 00:05:05,960 --> 00:05:08,440 Speaker 1: Works dot Com and for more podcast from my heart 90 00:05:08,520 --> 00:05:11,320 Speaker 1: Radio is the I heart Radio app, Apple Podcasts, or 91 00:05:11,360 --> 00:05:13,000 Speaker 1: wherever you listen to your favorite shows.