HowStuffWorks-Water

Water. It's the ultimate life support system. Water is the essence of life. It's so basic, but it's a flood of contradictions. Water is really hard. And it's stronger than a speed bullet. The bulletproof glass will stop a physical caliber shell, yet we can erode it with a water jet. We just can't seem to get enough of it. They would use 2000 gallons of water and maybe 30 miles. And now water on how stuff works. Silvery, intangible, just plain wet, water is all around us, yet it remains a mystery. While water makes up around 55% of our bodies, why will just a small amount cause a person to drown? Why are rivers fresh, but ocean salty? Why does solid ice float on liquid water? And can you really grow water from a seed? It's all part of how water works. Water is strange. It takes an unbelievable amount of water to grow a single apple, and almost 50 times more for a pound of beef, and there's 6 times more water in the sky over our heads than in the rivers under our feet. We all think we know water, but our understanding is, well, the muddy at best. Water. It dices its slices, it steams, spoons, and sprays. But for every plant or animal on the planet, the essence of water remains this, keeping us alive. A steel fender built for a custom motorcycle, and a ballistic grade material designed for bulletproof, blast proof armor. They're among the strongest engineering materials around. But today, they'll both be cut down to size by one of the world's most powerful forces. Forget about bubble baths and designer bottled water. This is the Seattle research lab of flow, international. The world's leader in ultra high pressure for UHP, what are jet cut in? So why is water a cut above a welding torch or diamond edged saw blade? It all begins simply enough. A hydraulic pump takes in regular tap water and pressurizes it. For water, increased pressure through a small aperture equals increased velocity. And since as we all remember from school, the force equals mass times acceleration, increased velocity means serious slice ability. You can take a very small fraction of Niagara Falls and push some drainage in a very small beam, and that will be able to cut very hard material. Just like laser, we focus the light to make a laser beam. The water is forced through this tiny opening, which is rained with a gemstone, so it won't be cut to shreds by the water jet. Just like constricting a garden hose with your thumb, concentrates a stream of water out of the nozzle, concentrating a volume of water through a tiny opening produces this. At the business end of the jet, the water is traveling faster than any jet plane at Mach four. Four times the speed of sound at a pressure of 87,000 pounds per square inch. So at that point, it's really one of the most powerful water jets on earth. How does water? The same soothing liquid we drink and bathe in. Cut through materials we use to build skyscrapers, the answer is one of water's grittiest abilities, erosion, the removal of solid material by the force of moving wind or water. Water starts eroding material, the second that it hits earth. The original processes begin with raindrops impacting the land surface. And as the raindrop hits the ground, it exerts quite a bit of force on those particles and can actually detach them and move them. Erosion also occurs in a river like the one that we're floating on here. The water is very powerful force. Certainly powerful enough to carve away a box. As it travels downstream, it carries along with it, all the little tiny particles of sediment, except along the way, sharing the sides and the bottom just with the force of its movement. The evidence of this one two punch water and moving sediment is everywhere. Like these grand canyons carved out by the Colorado River, some are a mile deep. The result of tens of millions of years of erosion. Back at the shop, high pressure water alone can slice materials as hard as glass. But throw in a little fine sand, and it can cut through pretty much anything. By adding abrasive to the water, you're increasing the strength of that water over a hundred times. And abrasive high speed water jet even shoes through incredibly hard ballistic ceramic and glass, used in the most advanced blast resistant armor. It's the unique characteristics of water and how erosion works. Bulletproof glass will stop a 50 caliber shell at 200 feet, but yet we can erode it with a water jet, just like we would have standard pieces of plate glass in your house windows. The water will also drill right through to the steel guide under the material. In fact, the only way to stop the water is with more water. A four foot deep trough of water helps absorb the 2400 mph jet before it bores a hole in the floor. What's the upside to using water as a cutting tool? Just about everything. What is inexpensive and reusable? It makes a very precise cut. And since it does its job without heat or friction, the cutting edge doesn't distort the material, and it never gets dull. Water is anything but dull. Water's physical properties, tufts get fluid. Make it the backbone of everything from tiny cells to the world's weather systems. It's a small simple molecule that covers 70% of the planet. It's a liquid that carves out the planet's surface and an electrically lopsided chemical that makes all life possible, and over time it cuts like a knife. But what makes it so tough? As in much of life, the key to success is sticking together. Water's countless molecules flow as if one. And that flow has everything to do with what are electrochemical makeup. Water is something called a dipole. The dipole simply means that it's a material that has one kind of charge on one end, and in another kind of charge, the opposite one on the other end. So it's got a slightly negative part over near the big fat oxygen atom and near the hydrogen atoms. It's a slightly positive part. So this enables water to do something pretty spectacular when it's in combination with other water molecules, the hydrogen parts get attracted to the oxygen part of its nearest neighbor. And so the molecules kind of squeeze together. This attraction, known as the hydrogen bond, is at the core of water's amazing properties. It makes water tough enough to provide a stiff but fluid structure of plants and animals. H2O is molecular structure, also allows for a truly miraculous transformation. As water freezes into a solid, the hydrogen bonds form a crystal lattice that has a lot of empty space in it. Unlike nearly every other substance known to man, it becomes less dense as a solid than a liquid, turning traditional physics on its head. The result, ice floats on water. Because of this, when we freeze a body of water, it freezes from the top down, not the bottom up. If ice didn't float, if water became more dense as it froze, then our ponds are lakes, our oceans, rivers, would freeze from the bottom up, and would eventually be solid ice. And would be much less conducive to life. The hydrogen bond enables life as we know it, but because of this bond, it takes considerable heat depending on volume, whether supplied by a stove or the sun itself, to raise water's temperature even 1°. This ability to absorb heat is known as heat capacity. Water actually has the second highest heat capacity of all of our common substances on the surface of the earth. With ammonia actually is the only common substance that has higher heat capacity. That's why we use water in cooling our internal combustion engines, our power plants, and the human body, the evaporation of perspiration. It keeps our temperature regulated. And similarly, one of the reasons that our change of seasons is rather than abrupt, is that water absorbs heat and releases it rather slowly. So the water on the planet tempers the change of seasons. The deep blue ocean suck up solar energy, much like the roof of a dark colored car on a sunny day. Acting as a planet wide heat engine that circulates water currents, air currents, and precipitation. The sun causes water to evaporate from dewdrops, upstreams, ponds, oceans, and lakes. The vaporized water rises, cools, forms clouds. And eventually condenses into rain droplets or snowflakes. It all comes back down to earth, and one way or another, whether it percolates into the ground water, or flows on the surface of lakes or streams, virtually all water eventually works its way back to the ocean. So what happens is in the cycle is repeated, all water on earth has been recycled in millions and millions of times. You probably have figured out that water equals life to begin with. It is the perfect medium in which life can form and reform. But why? What properties of water make it the fluid of life? Water has a very important role in all of the chemistry that happens. A huge array of materials will dissolve in water. And because water enables other things to dissolve in it, it provides a medium where those things can recombine and form new chemicals. Water takes a kind of divide and conquer approach to breaking down other chemicals. In the case of table salt or sodium chloride, water is negatively charged oxygen atoms surround the positive sodium ions. While the positive hydrogen atoms surround the negative chlorine ions by splitting the two elements apart, what are literally breaks down the structure of the salt. Moreover, because water remains liquid at the conditions of the surface of the earth, you can move around in all different kinds of directions. That's called degrees of freedom. So things can move around, flip around, vibrate, stretch, rotate, and then they're able to try novel combinations and hook up in new ways. This surely helped life get started on the early earth. The chemicals, the raw ingredients that make up life were constantly sloshing around. Bumping into each other and combining into new chemistry. Over millions of years, that process can lead to. Living organisms, but to really see water's life giving function. We need to check in with the plant kingdom. In a plant, an important function of water is structural. The plant cell is like a water balloon. It maintains its shape because of the pressure of water inside the cell, pushing out on the rigid cellulose wall. What are also has an almost magical ability as a chemical reactant. In other words, what are encourages chemical reactions that change the nature of other things? For instance, the chemical transformation that water makes possible within plants. So plants make their own food using light. It's called photosynthesis. And when they do photosynthesis, they take the hydrogen away from the oxygen in water, and they use the hydrogen with the carbon dioxide in the air to make sugar. It's alchemy. Luckily for us, animals, the chemical reaction also produces oxygen as a waste product. It's a totally wonderful relationship between plants and animals enabled by water. But plants and water have another dramatic impact on our atmosphere. Using a remarkable system, plants transport water from their roots to their leaves, where photosynthesis takes place. Water, with its high surface tension, the elastic quality of a liquid surface that makes it hard to break. Is able to travel up the vascular system of even the tallest trees. Once at the top, it evaporates back into the air through the leads or needles. A single redwood releases up to 500 gallons of the precious liquid through its needles in one day. So how does it get up there? A solar powered hydraulic pump. Water molecules, they attract each other. And for each water molecule that leaves the liquid column in the leaf, another molecule will move up. And the net result is that by evaporating off the surface of the leaf, we have a whole stream of water moving continually from the soil into the root and eventually out in the leaf. This silent invisible molecule by molecule movement of water upwards through a plant, represents the single biggest use of water by human beings. As a commodity, nothing in waters portfolio compares to irrigation. Especially in the western United States. If we look at water use in, for instance, the state of California, on Utah, or Arizona, the vast majority of water which is used for human purposes is used in irrigation. In the state of California, maybe 80% of our water use may be even more is utilized for irrigation for growing crops. In other words, the vast majority of our water becomes food. But it doesn't come easily. To grow even a single apple requires 25 gallons of water. And for every pound of meat, it takes about 1200 gallons of water. And in the United States, because we have a relatively high meat content in our diet, every day we use about 1600 gallons of water for every human just to produce the food that we eat. California, which grows the majority of the nation's fresh produce, is blessed with fertile soil and a year round growing season. But the Golden State and its neighbors from Nevada to Colorado don't have a lot of water. Or more accurately, the water tends to fall up here. In mountains up to 14,000 feet tall, the rest of the region, with few exceptions, ranges from semi arid to bone dry. The western states bold solution to this unequal distribution of water has been to dam the region's precious few rivers, including the Colorado, and avert them thousands of miles to lands that get as little as 7 inches of rain a year. When you look at the scale of water management, worldwide are over history, you can look at Ancient Rome and the aqueducts, but these things pale compared to the water projects in western North America. The Crown jewel in this system is Hoover Dam. Although completed over 70 years ago, Hoover Dam remains one of the most staggering achievements ever. It did the unthinkable, taming the wild Colorado River into giant Lake mead. The largest man-made reservoir in America. The whole back of a tremendous force is in pressure of the water in Lake mead. Hoover Dam is like a small mountain here in this canyon. It's 660 feet thick from front to back upstream to downstream. So it's just huge. Hundreds of feet of concrete and it's just such a massive and over 700 feet tall. It has to withstand at the base. A water pressure of about 45,000 pounds per square foot. Because behind it is Lake mead, which stretches for about a 110 miles. And holds something like 28 million acre feet of water when at capacity. So you can imagine this is not only a huge engineering feat in terms of its size, but the stresses that it is designed to bear are quite incredible. The dam was built primarily to bring water from the Colorado River to the dry farms and cities of California, Nevada, and Arizona. Today, water from the Colorado River supplies at least 25% of the nation's fresh produce. Depending on the time of year, maybe as much as 50%, that is a huge portion of our food supply in this country as a result of the Colorado Colorado River that is now controlled by Hoover Dam. Water will make the desert bloom. As long as you're willing to move it. The Colorado River shimmers in the summer sun. It's a jewel with many facets because the river's waters are unpredictable. Despite the fact that I wrote down this river, essentially on a daily basis, I really never tire of the beauty of this place. You don't find this in a cubicle. But just around the corner, water can turn from friend to deadly foe. A smooth flowing current becomes chaotic rabbits. I can't really think of a force that I encounter on a daily basis that even comes close to the power of its river. You turn your back once, you mess up in a small way, turn into a pretty big problem. What physical forces cause water to suddenly kick it into high gear. Usually by a combination of three different forces or actions within the water itself. The first is a gradient drop. It's the gradient is going down quickly. You can have some very, very swift water. Secondarily, we've got constriction. Different rock layers can create tighter channels. Going around a steep bend in the river can constrict the channel. And then the third thing is obstructions. Rock falling off the cliff wall, rock being swept into the river by flash floods. The steeper the gradient, the greater the change in velocity. The Colorado River makes one of the steepest drops of any major river in the United States, falling 13,000 feet in elevation between the Rocky Mountains and the gulf of California. Two other factors, constriction and obstruction, turn the Colorado River into a roller coaster ride. It's very incompressible. So when you try to squeeze a volume of water, its size doesn't get smaller, like many other materials. We have a fancy term for this. It's called bulk modulus, which is a function of how incompressible something is. Well, water is really hard. It might slip around a lot, but if you contain that volume, you can't compress it very much. Even hard metals can be compressed. So why not water? H2O dipole Bond causes water to move with greater force through whatever's trying to contain it, like a narrow canyon, folders in the riverbed, or a power plant. A jam the size of Hoover Dam is a triple threat. It tames floods, distributes irrigation water, and transforms water into power. But just how does a river have become electrical currents? It's all about harnessing water's nonstop downhill motion. The sheer height of the dam creates a huge difference in elevation between the upstream and downstream sides. As the water enters the intake towers, it falls about 700 feet. The potential energy that stored in a reservoir is proportional to the mass of the water that's stored in the reservoir. The potential energy is the mass times the acceleration of gravity times the height, the elevation at which the water is stored. In other words, the more water you have, and the farther you can make it fall, the more energy you can convert. So that potential energy then is converted to kinetic energy, is that massive water flows downhill. The gravity driven velocity of the water is increased by constriction, as it's forced through narrower and narrower pipes. Water is incompressible, but what happens is, is that same volume of water in order to get into a smaller area, it has to move faster. And that same thing happens when they use it for hydroelectric power. By the time the water enters one of the 17 turbine generators, it's moving at 60 mph. The speed and pressure of the water are powerful enough to rotate these 114 times shafts, 180 times per minute. Each shaft spins a rotor, which is built of large electromagnets and surrounded by a coil of copper wire. The magnetic field between the magnets and the coil generates a massive electric current. In a split second, water is transformed into power. One current becomes another. Hydroelectric power provides about 24% of the world's electricity. But harnessing the power of water has its downside. Dan's permanently flood vast ecosystems and damned reservoirs in hot, arid regions, like the lower Colorado basin, also tend to evaporate quickly, which makes the water saltier when it's released downstream. Also when you store the water in the reservoir, it changes the temperature of the water. So when it's released downstream, it may not be appropriate for some of the native plants and animals which lived in the water previous to the building of the dam. Damn or no dam, liquid water resumes its unstoppable course to the sea. The most diffuse state of water, steam is perhaps its most muscular form. Converted into steam, water becomes mechanical energy and lots of it. It takes a lot of energy to raise water's temperature, and even more to go from liquid water into a gas. For all the heat energy needed to bring water to the point of boiling, it takes 7 times that energy to then turn the boiling water into steam. But let's say you do apply huge amounts of energy. In this case, heat from wood and coal burned inside a pressurized boiler. Well, that energy can be converted into something, including mechanical energy. So when water becomes a gas, and that gas is less dense than the liquid part, you can use that gas to create a force as it expands. So we can use steam to power motors. Steam, the pure gas form of water has its own peculiar properties. As it expands, it occupies 1600 times the volume of liquid water, creating a great mechanical kick that can be harnessed to do work. That's the idea behind the machine that changed the world forever. The steam locomotive. On engine cars like these, the idea begins with water. Lots of it. We're standing on top of the tender tank. It's a great big U shaped tank and it holds 2000 gallons of approximately. The water is pumped from the Tinder tank to the boiler, a fuel source wood or coal is prepared to be burned. We put a fire underneath it and boil water. And capture that and expand in water in the pressure. Works in 5 fortune against something solid as it expands out. That's how we get the motion. The steam bangs against the pistons, which then drive the wheels, moving the train along the track. Until it must stop for more water. It's easy to forget that in their heyday, these trains ran on water as much as they did, wood or coal. They would use 2000 gallons of water in every 30 miles. So they had stopped every 30 miles more for the water than the wood. Steam, for all its power, is invisible. The white vapor cloud we see coming from a locomotive is actually missed. Tiny vapor droplets that form as the steam cools and condenses in the air. If you look at the spout of a steaming tea kettle, the spot where there appears to be nothing, that steam. At the opposite extreme of water's life cycle, H2O takes on a much more visible form in ice. The solid form of water has everything to do with how water is distributed on earth, and remember it's less dense as a solid than as a liquid. So where does water go to slow down and kick back? Not surprisingly. Canada, where you'll find 20% of the world's fresh water, much of it frozen in the form of glaciers. There remain a great number of glaciers in the Canadian west. There are more than 5000 glaciers in the mountains that separate the great plains from the Pacific Ocean. But the largest ice mass in this region is the Columbia ice field. It covers about 325 km², and is in some places nearly a thousand meters deep. The Columbia ice field is North America's hydrological apex, or triple continental divide. Meaning that from this 12,000 foot high summit, the melting ice will eventually feed into three different oceans, the Arctic, the Pacific, and the Atlantic. It's an incredibly rare phenomenon. Glaciers are formed through cumulative snowfall. Snow builds up, it's compressed by its own weight and begins to form into ice. And as that accumulation continues beyond 30 meters, the ice will begin to change its shape and internal characteristics and begin to flow. This water has been captured by the cold air, where it's been trapped for as much as tens of thousands of years. But despite its solid appearance, frozen water can still flow. Glaciers move. They're slowly moving rivers of ice that much like liquid rivers, carve out valleys and prairies. Glaciers with their slow but steady summer melt are also key to the distribution of water on earth. In fact, 75% of the world's fresh water is stored in glaciers. The Columbia ice field is rare in another sense. The water here is pure enough to drink, right from the stream. Look up into the atmosphere. And what you're really seeing are liquid skies. If only we could cook some of that water vapor down to earth in arid regions of the globe. But wait, we can by putting tiny seeds into the clouds. Some scientists estimate that the amount of water loading in the Earth's atmosphere is 6 times greater than that flowing in all the world's rivers. But most of that airborne water is in the form of vapor. When that vapor rises high into the atmosphere, it cools and condenses into tiny droplets of water or ice. Each about 200s of a millimeter across, these droplets gather into what we see as clouds. But how do clouds become rain? It's not so easy. In one of the more peculiar of waters many peculiar properties, the droplets not unlike a pearl, must form around a tiny imperfection. A bit of dust or debris known as a cloud condensation nucleus, or a cloud seed. In order to grow heavy enough to fall from the sky. This tiny trick of nature is not happening often enough in some parts of the world, like the Texas south plains region, which has experienced frequent and severe droughts in recent years. Making things worse, the ogallala aquifer, which provides irrigation water to parts of 8 western states, including Texas, is being sucked dry faster than rainfall can replenish it. And so, Gary walker and his company soar perform a high-tech version of The Rain dance, an attempt to ring precious water from clouds that just don't want to rain. In this area, the two main sources of water are the ogallala aquifer, which is an underground aquifer and rainwater. In possibly the next ten to 20 years, there would not be the capability to pump enough water out of the aquifer, irrigation purposes. Source proposed solution is known as cloud seeding. Gary's going to fly his twin engine piper into a cloud, armed with rocket flares of silver iodide, the silver iodide particles will act as cloud condensation nuclei. The particles are extremely tiny. There's about 13 trillion particles are still red out in that 20 gram player right there. We're now ready to go on a seating mission. First, the plane must find a suitable cloud at an altitude of 18,000 feet, where the supercooled water droplets might be ready to form raindrops. Meteorologist James dryden guides Gary walker's plane into position. All right, see, one basically you're approaching me in New Mexico state border. So we need to go ahead and turn around. Yeah, let's go ahead and get you on the south side of the storm from your current location to track would be two O three at night or nautical miles. Charlie, we're going to penetrate and about 11,000. Gary fires the silver iodide flares into the cloud. There goes some player, good updrafts, thousand feet a minute, there's another player. The updrafts carry the silver iodide particles into the upper regions of the cloud. If the conditions are just right, we can expect to see raindrops falling in less than 45 minutes. But today, there's simply not enough water vapor to form raindrops. Another dry day in Texas. But the cloud seeding program has made a difference. Our analysis has shown about ten to 12% additional rainfall out of seated clouds versus non seated clouds and that would equate to about another inch to an each .2 of rainfall during the growing season. So if we create an inch of water over our seating area in the summertime, it's thousands and thousands of acre feet of water. In an era of accelerated climate change, reliable water supplies will be harder to come by. Here on the Texas plains, and back at the Columbia ice field, where global warming is threatening the ancient stores of glacial water. Glaciers are water in the back that is water held from earlier historical times. And carried into our time and when it melts, it contributes to the flow regimes of existing river systems. If glaciers are water in the bank, there's a run on that bank in the form of accelerated melt. Like many other glaciers, the four mile long athabasca glacier is receding dramatically, and losing vertical mass. With year after warm year the rapid melting will mean more flooding, but in a cruel paradox, less opportunity to harness the water. We've gotten used to having. What will happen is that we will have less water than we have designed our systems for. And therefore, we'll be facing water scarcity in many parts of the country that never face water scarcity in late summer before. 21st century water scarcity is yet another challenge for human beings, as we struggle mightily with the fluid of life. Bringing it to places that would otherwise never see it. Transforming it into power, machinery, and abundance. Reclaiming it from the oceans, sewers. And even rearranging the weather to make more of it fall to earth. But water in its utter uniqueness, stubbornly resist change. It will always seek its downhill path. From the mountains to the sea. It will continue to dissolve whatever it picks up along the way. It will refuse to be compressed, and it will not create any more of itself, no matter what we do. What happens to this river happens to us. It may not happen immediately, but it will have some eventually. All of those actions have repercussions on us as humans, and as a civilization. I think it would behoove us to be a little more mindful of what we do to our rivers. Keeping them a little more pristine, a little more wild, a little cleaner. We're definitely do as good as a society.