WEBVTT - Why Is the Ocean Different Colors? 0:00:01.920 --> 0:00:07.160 Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff, 0:00:07.200 --> 0:00:10.879 Lauren Vogal Bomb. Here, someone gazing out at the ocean 0:00:10.920 --> 0:00:14.160 from the main coast sees very different hues than someone 0:00:14.240 --> 0:00:16.079 squinting at the sea from a sunny beach on a 0:00:16.120 --> 0:00:19.160 Greek island. But why does the ocean come in so 0:00:19.200 --> 0:00:23.640 many shades of blue? Of course, ocean water isn't inherently blue. 0:00:23.680 --> 0:00:26.280 It's clear the colors that we see on the surface 0:00:26.320 --> 0:00:28.920 are the result of light being absorbed and reflected by 0:00:28.960 --> 0:00:31.400 the water itself, whatever is floating and living in it, 0:00:31.560 --> 0:00:35.199 and the surface of the ocean floor below it. A 0:00:35.240 --> 0:00:37.960 glass of water will of course appear clear as visible 0:00:38.000 --> 0:00:41.000 light passes through it with little to no obstruction. But 0:00:41.120 --> 0:00:43.080 if a body of water is deep enough that light 0:00:43.159 --> 0:00:47.680 isn't reflected off the bottom, it appears blue. Basic physics 0:00:47.680 --> 0:00:50.640 explains why light from the sun is made up of 0:00:50.640 --> 0:00:54.120 a spectrum of different wavelengths. The longer wavelengths appear to 0:00:54.120 --> 0:00:56.720 our eyes as the reds and oranges, while the shorter 0:00:56.800 --> 0:01:00.960 ones appear blue and green. When the Sun's strikes the ocean, 0:01:01.200 --> 0:01:04.280 it interacts with water molecules and can be either absorbed 0:01:04.400 --> 0:01:07.800 or scattered. If nothing is in the water except water. 0:01:08.240 --> 0:01:10.679 The longer red portions of the spectrum tend to be 0:01:10.720 --> 0:01:14.120 absorbed by the water molecules, whereas the light of those 0:01:14.120 --> 0:01:17.119 shorter wavelengths is more likely to go deep, hit water 0:01:17.160 --> 0:01:20.360 molecules there, and scatter back up towards our eyes, making 0:01:20.360 --> 0:01:24.920 the ocean appear blue. Depth and the ocean bottom also 0:01:24.959 --> 0:01:27.720 influence whether the surface appears a dusky dark blue, as 0:01:27.760 --> 0:01:30.759 in parts of the Atlantic, or casts a sapphire like shiver, 0:01:30.920 --> 0:01:35.119 as in many tropical locations. We spoke with NASA oceanographer 0:01:35.319 --> 0:01:39.480 Jeane carl Feldman. He said, in Greece, the water is 0:01:39.520 --> 0:01:42.360 this beautiful turquoise color because the bottom is either white 0:01:42.360 --> 0:01:46.039 sand or white rocks. What happens is the light comes 0:01:46.080 --> 0:01:48.720 down and blue light gets down, hits the bottom, and 0:01:48.720 --> 0:01:51.480 then reflects back up, So you make this beautiful light 0:01:51.520 --> 0:01:55.640 blue color in the water. Darker sand rocks or other 0:01:55.680 --> 0:02:00.760 formations mean darker water. The color is further complicated by 0:02:00.800 --> 0:02:03.120 the fact that the ocean is rarely just water, but 0:02:03.280 --> 0:02:06.240 is instead teeming with tiny plant and animal life, plus 0:02:06.320 --> 0:02:11.280 suspended sediment or other natural or band made contaminants. Oceanographers 0:02:11.280 --> 0:02:13.960 monitor the ocean's color the way that doctors read vital 0:02:14.000 --> 0:02:17.200 signs of their patients. Colors seen on the ocean's surface 0:02:17.360 --> 0:02:22.320 reflect what's going on in its vast depths. Feldman, who 0:02:22.400 --> 0:02:25.040 is based at the NASA Goddard Space Flight Center in Maryland, 0:02:25.240 --> 0:02:28.440 studies images taken by the sea viewing wide field of 0:02:28.520 --> 0:02:33.120 view since her satellite launched in from its perch more 0:02:33.160 --> 0:02:35.760 than four hundred miles above Earth or nearly six hundred 0:02:35.840 --> 0:02:39.359 fifty kilometers, The satellite captures van go like swirls with 0:02:39.400 --> 0:02:43.120 the ocean's colors. The patterns are not only mesmerizing, but 0:02:43.160 --> 0:02:45.920 they also reflect where sediment and runoff may make water 0:02:46.000 --> 0:02:49.840 appear a dull brown, and where microscopic plants called phytoplankton 0:02:50.000 --> 0:02:55.119 collect in nutrient rich waters, often tinting it green. Phytoplankton 0:02:55.240 --> 0:02:58.160 used chlorophyll to capture energy from the sun to convert 0:02:58.240 --> 0:03:02.560 water and carbon dioxide into energy and then waste. Through 0:03:02.560 --> 0:03:06.360 this process called photosynthesis, phytoplankton generate about half of the 0:03:06.400 --> 0:03:11.360 oxygen we breathe. Oceans with high concentrations of phytoplankton can 0:03:11.400 --> 0:03:14.560 appear blue green to green, depending on the density. Some 0:03:14.680 --> 0:03:18.480 lend the water a yellow, reddish or brown tint. Phytoplankton 0:03:18.600 --> 0:03:21.079 serve as the base of the food web and primary 0:03:21.080 --> 0:03:24.120 source of food for zooplankton, which are tiny animals eaten 0:03:24.120 --> 0:03:26.720 by fish. The fish are then eaten by bigger animals 0:03:26.760 --> 0:03:31.200 like whales and sharks. It's when oceans become polluted with 0:03:31.280 --> 0:03:34.760 runoff that the amount of phytoplankton can escalate to unhealthy levels. 0:03:35.400 --> 0:03:39.240 Phytoplankton feed on the pollutants, flourish, and then die, sinking 0:03:39.240 --> 0:03:41.640 to the bottom to decompose in a process that depletes 0:03:41.680 --> 0:03:46.040 oxygen from the water. Over the past fifty years, ocean 0:03:46.160 --> 0:03:49.160 zones with depleted oxygen have more than quadrupled to an 0:03:49.200 --> 0:03:52.480 area roughly the size of the European Union. Part of 0:03:52.520 --> 0:03:54.960 the cause may be an increase in ocean temperature due 0:03:55.000 --> 0:03:59.680 to climate change, since warmer water supports less oxygen. In 0:04:00.040 --> 0:04:03.000 still areas, phytoplankton blooms are suspected to be the cause. 0:04:04.000 --> 0:04:06.520 Phytoplankton may serve as the base of the ocean food chain, 0:04:06.760 --> 0:04:08.880 but as Feldman says, too much of a good thing 0:04:09.040 --> 0:04:12.120 is not a good thing. On a map on Feldman's 0:04:12.120 --> 0:04:14.720 office wall is a marker showing where there's little human 0:04:14.760 --> 0:04:18.080 interference and ocean water is perhaps the clearest on the planet. 0:04:18.839 --> 0:04:20.919 In this region, off the coast of Eastern Island in 0:04:20.920 --> 0:04:24.240 the Southeast Pacific Ocean. The water is deep and remarkably 0:04:24.279 --> 0:04:26.120 clear due to its location in the middle of a 0:04:26.160 --> 0:04:30.159 giant oceanic eye, which is a large circular current. Its 0:04:30.160 --> 0:04:33.479 central location means there's minimal mixing of ocean layers and 0:04:33.560 --> 0:04:36.880 nutrients aren't pushed up from the deep bottom. The purity 0:04:36.920 --> 0:04:39.039 of the water they're coupled with the depth make the 0:04:39.080 --> 0:04:43.960 ocean appear a deeper indigo than perhaps anywhere else. Feldman said, 0:04:44.320 --> 0:04:47.720 the light just keeps going down, down, down. There's nothing 0:04:47.720 --> 0:04:50.800 that bounces it back. Here is the deepest blue you'll 0:04:50.839 --> 0:04:59.080 ever see. Today's episode writtain by Amanda Onion and produced 0:04:59.080 --> 0:05:01.479 by Tyler Clang. Brain Stuff is a production of I 0:05:01.560 --> 0:05:03.640 Heart Radio's How Stuff Works. For more in this and 0:05:03.720 --> 0:05:05.800 lots of other topics is our Home Planet has to 0:05:05.960 --> 0:05:08.440 Works dot Com and for more podcast from my heart 0:05:08.520 --> 0:05:11.320 Radio is the I heart Radio app, Apple Podcasts, or 0:05:11.360 --> 0:05:13.000 wherever you listen to your favorite shows.