1 00:00:00,000 --> 00:00:04,320 This is a glass of water, and it's been on a long, long trip. 2 00:00:04,719 --> 00:00:08,000 I'm serious. It didn't pack any bags or take any selfies along the way, 3 00:00:08,179 --> 00:00:11,919 but this water has been around the world many, many times. 4 00:00:15,419 --> 00:00:23,739 Think I'm crazy? I'm not. 5 00:00:23,980 --> 00:00:27,859 This water is part of a long, worldwide system called the water cycle. 6 00:00:27,940 --> 00:00:31,920 The water cycle explains the way water moves on, above, and below the Earth. 7 00:00:32,060 --> 00:00:33,460 And it's huge! 8 00:00:33,640 --> 00:00:36,880 It includes every giant glacier and every tiny little puddle. 9 00:00:36,880 --> 00:00:41,060 It includes the water at the bottom of the ocean and the water in the clouds in the sky. 10 00:00:41,200 --> 00:00:42,700 As you know, water is matter. 11 00:00:43,000 --> 00:00:44,859 And we've learned that matter can change states. 12 00:00:45,219 --> 00:00:47,740 It can be a solid, a liquid, or a gas. 13 00:00:48,140 --> 00:00:51,939 For water, that means it can be ice, liquid water, or water vapor. 14 00:00:52,159 --> 00:00:56,520 And as all of this water, which makes up the hydrosphere, winds its way around the world, 15 00:00:56,700 --> 00:00:58,719 it interacts with the other three spheres. 16 00:00:58,920 --> 00:01:01,719 It starts, as many things do, with the sun. 17 00:01:01,859 --> 00:01:02,479 Hey, buddy! 18 00:01:02,479 --> 00:01:15,030 As the sun sends its energy down to the earth, the surface of the oceans and lakes are heated until some of the liquid water turns into a gas, water vapor. 19 00:01:15,030 --> 00:01:17,030 This process is called evaporation. 20 00:01:17,030 --> 00:01:20,030 Have you ever dried off in the hot sun after a dip in the pool? 21 00:01:20,030 --> 00:01:23,030 If you have, you've experienced evaporation. 22 00:01:23,030 --> 00:01:28,030 After the water evaporates, the water vapor rises higher and higher into the atmosphere. 23 00:01:28,030 --> 00:01:31,030 As it goes up, it starts to cool, which makes a lot of sense. 24 00:01:31,030 --> 00:01:35,030 You've probably noticed that the tops of tall mountains are cold and snowy. 25 00:01:35,030 --> 00:01:36,790 Sometimes, even in the summer. 26 00:01:36,790 --> 00:01:41,450 So as the water vapor rises, it eventually gets cooler and starts to turn into liquid. 27 00:01:41,450 --> 00:01:43,150 This is called condensation. 28 00:01:43,150 --> 00:01:46,969 All those little water molecules start sticking together, along with the particles of dust 29 00:01:46,969 --> 00:01:51,349 and other tiny bits of stuff, turning into a mass of small drops of condensed water that 30 00:01:51,349 --> 00:01:52,349 we call clouds. 31 00:01:52,349 --> 00:01:57,069 And when it's all snuggled up in the clouds, water can do some serious traveling, because 32 00:01:57,069 --> 00:02:02,129 wind and other air currents can push clouds over long distances, so the water in the clouds 33 00:02:02,129 --> 00:02:05,890 above you may have originally been picked up over a faraway ocean. 34 00:02:05,890 --> 00:02:10,710 Now, if enough water particles in a cloud stick together, then the water will fall out. 35 00:02:10,710 --> 00:02:13,250 And when it does, it's called precipitation. 36 00:02:13,250 --> 00:02:17,189 It takes millions of cloud droplets to produce just one raindrop. 37 00:02:17,189 --> 00:02:21,129 If the clouds are cold enough, they can form other kinds of precipitation, too. 38 00:02:21,129 --> 00:02:25,689 Ice crystals can form in the clouds, for example, growing bigger and heavier until they fall 39 00:02:25,689 --> 00:02:28,210 in the form of snow, sleet, or hail. 40 00:02:28,210 --> 00:02:32,129 No matter what form it takes, though, once the water falls, it can go in a couple of 41 00:02:32,129 --> 00:02:33,210 different routes. 42 00:02:33,210 --> 00:02:36,729 Some of the water will hit the ground and run towards streams and rivers, where it will 43 00:02:36,729 --> 00:02:38,389 eventually join the ocean. 44 00:02:38,389 --> 00:02:41,650 Some of it will soak into the ground through tiny pores in the soil. 45 00:02:41,650 --> 00:02:46,469 This water can collect and hang out underground for years until it slowly moves into the sea. 46 00:02:46,469 --> 00:02:49,370 Or it can be pumped up to be used as drinking water. 47 00:02:49,370 --> 00:02:53,870 And some of that water that rained down will also quickly be evaporated again. 48 00:02:53,870 --> 00:02:59,469 This whole process – evaporation, condensation, and precipitation – is repeated over and 49 00:02:59,469 --> 00:03:03,250 over, moving water all around the world, empowering weather events. 50 00:03:03,250 --> 00:03:07,750 We have the water cycle to thank for hurricanes, blizzards, and that rainstorm that caught 51 00:03:07,750 --> 00:03:09,650 me outside without an umbrella the other day. 52 00:03:09,650 --> 00:03:13,009 But you can also watch the water cycle happen in your own kitchen. 53 00:03:13,009 --> 00:03:18,120 Let's investigate. 54 00:03:18,120 --> 00:03:22,460 First, pour hot water into a clear bowl, then cover it with plastic wrap and place a few 55 00:03:22,460 --> 00:03:23,699 ice cubes on top. 56 00:03:23,699 --> 00:03:27,419 In this experiment, the hot water is water that has been heated by the sun, and the wrap 57 00:03:27,419 --> 00:03:29,840 with the ice cubes is the cool atmosphere. 58 00:03:29,840 --> 00:03:32,740 Molecules in the hot water rise in the form of water vapor. 59 00:03:32,740 --> 00:03:36,439 Once they hit the cool atmosphere, which is our plastic wrap, you can see the molecules 60 00:03:36,439 --> 00:03:39,979 condense on the underside of the wrap into drops of liquid water. 61 00:03:39,979 --> 00:03:44,219 Once there's enough condensation, water droplets will fall back into the bowl. 62 00:03:44,219 --> 00:03:45,219 It's raining! 63 00:03:45,219 --> 00:03:53,069 You've just created a tiny adorable water cycle all on your own. 64 00:03:53,069 --> 00:03:55,389 Let's cycle back and review what we've learned. 65 00:03:55,389 --> 00:03:59,750 Energy from the sun powers the water cycle, a process that moves water around the globe 66 00:03:59,750 --> 00:04:05,069 through evaporation as the water rises, condensation as it forms into clouds, and precipitation 67 00:04:05,069 --> 00:04:09,169 as it falls back down in the form of rain, snow, sleet, or hail. 68 00:04:09,169 --> 00:04:13,870 Water moves through the system over and over again, changing forms and visiting every corner 69 00:04:13,870 --> 00:04:14,870 of the Earth. 70 00:04:14,870 --> 00:04:18,509 I bet you've got a whole new respect for this glass of water, huh?