what is the water cycle?
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precipitation ,condensation & evaporation
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Water, nitrogen and carbon.
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http://en.wikipedia.org/wiki/Image:Water_cycle.png
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Water is created by burning hydrogen.
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Ooh, I studied this last semester. It changes phase. In other words, it changes from liquid (water) to gas (clouds) to liquid or solid (rain, snow, or hail). Then it repeats.
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Waves are the flow of energy through water.  There's quite a bit of energy in water and it can easily move as water is liquid, thus you observe a wave.  The water isn't actually moving much; each water molecule is moving just a bit and pushing the next molecule, which does the same and on it goes..
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Water loss from leaves is called transpiration and is greatest when it is hot.\nWhen a mass of warm, moist air is cooled the water vapour will condense and clouds are seen. As cooling progresses the droplets coalesce and fall as rain.\nThis cycle is most obvious in rain forests.\nBoth transpiration and evaporation from the sea and lakes contribute to water vapour in the air, but over continental areas transpiration from trees is of greater importance. Deforestation in these areas leads to dessertification.
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Capillary forces and water potential.  The water potential is the tendency of water to move from one place to another, due to evaporation or stuff dissolved in the water.
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In the water cycle, water falls to the earth in the form of precipitation.  Plant roots absorb the water, which is then transported through the xylem vessels to the leaves.  There, photosynthesis takes place.  Each water molecule is split up, forming hydrogen ions, oxygen, and electrons.  The electrons are used to create ATP for the dark reactions.  In end, a three-carbon sugar is formed, which combines with another three-carbon sugar to form glucose.  Besides photosynthesis, water seeps into the ground and bodies of water.  It stays there for organisms to use.  Much of it eventually evaporates.\nCO2 is used in photosynthesis to form glucose (the glucose's carbon is from CO2).  Glucose is eventually broken down to form ATP.  Animals store glucose in the form of gylcogen, whereas plants tore it in the form of starch.  Carbon is also present in the atmosphere in the form of other gases (including, I think, greenhouse gases).  It is also present in decaying organic matter, returning to the atmosphere in the form of gas.
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Water isn't important for everything. It's only important for living things such as plants, human beings, and small bacteria. Water is the one and only thing that could give you energy and rehydrate you completely. Water as the last person said has 2 hydrogen atoms and 1 oxygen atom. Those gases are helpful for your body to function.
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As you know, the Earth is a watery place. Estimates vary, but somewhere between 70 and 75 percent of the Earth's surface is water-covered. But water also exists in the air as water vapor and in the ground as soil moisture and in aquifers. Thanks to the water cycle (view a graphic of the water cycle) our planet's water supply is constantly moving from one place to another and from one form to another. Things would get pretty stale without the water cycle!\n\nWhen you take a look at the water around you, you see water in streams, rivers, and lakes. You see water sitting on the surface of the earth. Naturally, this water is known as "surface water." Your view of the water cycle might be that rainfall fills up the rivers and lakes. But, how would you account for the flow in rivers after weeks without rain? In fact, how would you account for the water flowing down this driveway on a day when it didn't rain? The answer is that there is more to our water supply than just surface water, there is also plenty of water beneath our feet.\n\nEven though you may only notice water on the Earth's surface, there is much more water stored in the ground than there is on the surface. In fact, some of the water you see \n\nThere is about 323 billion gallons  of surface water and about 85 billion gallons  of ground water.
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The Krebs cycle, also called the Citric Acid Cycle, is a method by which cells undergo aerobic cellular respiration.
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Recycling. Electrolyse of water. Plants give O2.\nCompressed and deep cooled liquid O2.
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the water is relesed as vapor from the liquid when the liquid is heated. Water changes phase and becomes gas, its called evaporation.
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The normal cycle is (very simplified): rain, transportation to sea, evaporation.\n\nThe main thing that mankind does to change this is after the rain has fallen and before it reaches the sea.  The main thing being irrigation which diverts water from the river into the surrounding land.  Obviously when water is soaked into the ground it cannot evaporate and so the 'residence time' in this part of the cycle is increased.\nBuilding damns and other structures (ie. cities) will also have similar effects by diverting the natural course of a river.\nWith global warming comes another problem.  Obviously the warmer something is the more energy it has.  This extra energy causes an unstable atmosphere leading to increased rainfall in some areas and less in others.  Rising sea temperature, which is also connected to global warming, will increase the rate of evaporation (which is why there are more hurricanes in the Atlantic).
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"Rain plays a major role in the hydrologic cycle in which moisture from the oceans evaporates, condenses into clouds, precipitates back to earth, and eventually returns to the ocean via streams and rivers to repeat the cycle again. There is also a small amount of water vapor that respires from plants and evaporates to join other water molecules in condensing into clouds"\n\n" 90% of atmospheric water comes from evaporation, while the remaining 10% is from transpiration."\n\n The total amount, or mass, of water in the water cycle remains essentially constant, as does the amount of water in each reservoir of the water cycle. This means that rate of water added to one reservoir must equal, on average over time, the rate of water leaving the same reservoir.\n\nThe adjacent table (at the site below) contains the amount of water that falls as precipitation or rises as evaporation, for both the land and oceans. The runoff and groundwater discharge from the land to the oceans is also included. From the law of the conservation of mass, whatever water moves into a reservoir, on average, the same volume must leave. For example, 107 thousand cubic km (107 × 10³ km³) of water falls on land each year as precipitation. This is equal to the sum of the evaporation (71 × 10³ km³/year) and runoff (36 × 10³ km³/year) of water from the land."
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The Hydrologic Cycle o Water Cycle\n\nThe hydrologic cycle is a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere, and the hydrosphere. Water on this planet can be stored in any one of the following reservoirs: atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater.\n\nWater moves from one reservoir to another by way of processes like evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow. The oceans supply most of the evaporated water found in the atmosphere. Of this evaporated water, only 91 % of it is returned to the ocean basins by way of precipitation. The remaining 9 % is transported to areas over landmasses where climatological factors induce the formation of precipitation. The resulting imbalance between rates of evaporation and precipitation over land and ocean is corrected by runoff and groundwater flow to the oceans.\n\nThe planetary water supply is dominated by the oceans. Approximately 97 % of all the water on the Earth is in the oceans. The other 3 % is held as freshwater in glaciers and icecaps, groundwater, lakes, soil, the atmosphere, and within life.\n\nWater is continually cycled between its various reservoirs. This cycling occurs through the processes of evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow. On average water is renewed in rivers once every 16 days. Water in the atmosphere is completely replaced once every 8 days. Slower rates of replacement occur in large lakes, glaciers, ocean bodies and groundwater. Replacement in these reservoirs can take from hundreds to thousands of years. Some of these resources (especially groundwater) are being used by humans at rates that far exceed their renewal times. This type of resource use is making this type of water effectively nonrenewable.\n\nALSO CHECK\n\nhttp://www.physicalgeography.net/fundamentals/studyguide_ch8.html