EvaporationAs water molecules evaporate, they take with them some of the heat from the object from which they evaporated. This heat is stored in the water molecule, and is referred to as latent heat. The result is that the object’s temperature is lowered slightly. Consider what happens to your body on a hot day. As the temperature rises, your body begins to produce sweat. As the sweat evaporates it carries with it some of the heat from your body, causing your body to cool down.
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Condensation images
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CondensationUsually in order for condensation to take place, the atmosphere must be fully saturated. In other words, the maximum vapor pressure must have been reached.
In addition to being saturated, the nature of water requires that there be a surface upon which water can condense. This surface might be blades of grass or windows. In the atmosphere, condensation often takes place around dust particles or other particulates such as smoke and even microscopic bacteria. |
PrecipitationPrecipitation takes place when water condensation becomes sufficient that water droplets are heavy enough to fall back to the surface of the Earth. Precipitation is a very common phenomena in the atmosphere of our Earth. This precipitation always comes from clouds. Yet most clouds do not form precipitation.
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precipitation.jpg http://www.savingwater.org/waterconnection/images/precipitation.jpg
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RunoffWhen rain hits saturated or impervious ground it begins to flow overland downhill. It is easy to see if it flows down your driveway to the curb and into a storm sewer, but it is harder to notice it flowing overland in a natural setting. During a heavy rain you might notice small rivulets of water flowing downhill. Water will flow along channels as it moves into larger creeks, streams, and rivers. This picture gives a graphic example of how surface runoff (here flowing off a road) enters a small creek. The runoff in this case is flowing over bare soil and is depositing sediment into the river. The runoff entering this creek is beginning its journey back to the ocean.
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Water shed
We all live in a watershed — the area that drains to a common waterway, such as a stream, lake, estuary, wetland, aquifer, or even the ocean — and our individual actions can directly affect it. Working together using a watershed approach will help protect our nation's water resources.
Information is from http://water.epa.gov/type/watersheds/index.cfm
Information is from http://water.epa.gov/type/watersheds/index.cfm
There's a whole lot of water on Earth! Something like 326,000,000,000,000,000,000 gallons (326 million trillion gallons) of the stuff (roughly 1,260,000,000,000,000,000,000 liters) can be found on our planet. This water is in a constant cycle -- it evaporates from the ocean, travels through the air, rains down on the land and then flows back to the ocean.
The oceans are huge. About 70 percent of the planet is covered in ocean, and the average depth of the ocean is several thousand feet (about 1,000 meters). Ninety-eight percent of the water on the planet is in the oceans, and therefore is unusable for drinking because of the salt. About 2 percent of the planet's water is fresh, but 1.6 percent of the planet's water is locked up in the polar ice caps and glaciers. Another 0.36 percent is found underground in aquifers and wells. Only about 0.036 percent of the planet's total water supply is found in lakes and rivers. That's still thousands of trillions of gallons, but it's a very small amount compared to all the water available.
The oceans are huge. About 70 percent of the planet is covered in ocean, and the average depth of the ocean is several thousand feet (about 1,000 meters). Ninety-eight percent of the water on the planet is in the oceans, and therefore is unusable for drinking because of the salt. About 2 percent of the planet's water is fresh, but 1.6 percent of the planet's water is locked up in the polar ice caps and glaciers. Another 0.36 percent is found underground in aquifers and wells. Only about 0.036 percent of the planet's total water supply is found in lakes and rivers. That's still thousands of trillions of gallons, but it's a very small amount compared to all the water available.