Are you drinking the same water a dinosaur drank? Could you be drinking the same water a saber tooth tiger lapped up?Water on earth moves in a What do you think? Iscontinuous cycle. This is called the water we have onTHE WATER CYCLE. There earth today the sameis about the same amount of water that was herewater on earth now that there millions of years ago?was when the dinosaursroamed our planet.
The cycle starts when the suns heat providesenergy to evaporate water from the surface.Then, winds lift the water vapor from the oceanover the lands into the atmosphere. The watervapor condenses to form clouds, and when theconditions are just right, the clouds release wateras rain or snow. About 80% of the rain falls in theoceans, but the rest falls onto land. Rivers andstreams collect water from the ground and returnit to the ocean so the whole cycle can start allover again. The water cycle never ends becausethe salty ocean water constantly supplies freshwater to the continents.
One process which tranfers water from the ground backto the atmosphere is evaporation. Evaporation is whenwater passes from a liquid phase to a gas phase. Ratesof evaporation of water depend on factors such as solarradiation, the temperature, humidity, and wind.Water that is held in lakes and rivers evaporates directlyinto the atmosphere, but some of the water in the groungmay also be returned to the atmosphere by way of evaporation through the soil surface. Of course, the ocean is the greatest source for water evaporated into the atmosphere.
Condensation is the change of water from its gaseous form(water vapor) into liquid water. Condensation generallyoccurs in the atmosphere when warm air rises, cools andlooses its capacity to hold water vapor. As a result, excesswater vapor condenses to form cloud droplets.
Precipitation is the main way for transporting water fromthe atmosphere to the surface of the earth. There areseveral forms of precipitation, the most common of whichfor the United States is rain. Other forms of precipitationinclude; hail, snow, sleet, and freezing rain.
Groundwater is all the water that has gone through theearths surface and is found in one of two soil layers. Theone nearest the surface is the "zone of aeration", wheregaps between soil are filled with both air and water. Belowthis layer is the "zone of saturation", where the gaps arefilled with water.
Transpiration is the process by which plants returnwater to the atmosphere. After absorbing water fromthe ground, plants release water through their leaves.Transpiration helps plants stay cool, in the same wayperspiration keeps humans and animals cool.
Runoff is the movement of land water to the oceans, mostlyin the form of rivers, lakes, and streams. Runoff consists ofprecipitation that hasn’t evaporated, transpired orpenetrated the surface to become groundwater. Even thesmallest streams are connected to larger rivers that carrybillions of gallons of water into oceans worldwide.
The Suns heatprovides energy toevaporate water fromthe Earths surface(oceans, lakes, etc.).
Evaporation occurs whenheat is placed on wateruntil the temperaturebecomes warm enough tochange water into a gas.
Condensation isthe cooling ofwater vapor untilit becomes aliquid. As the dewpoint is reached,water vaporforms tiny visiblewater droplets.When thesedroplets form inthe sky and otheratmosphericconditions arepresent, cloudswill form.
When the clouds meet cool air over land, precipitation(rain, sleet, or snow) is triggered, and water returns to theland (or sea).
A long, long, long time later, two very bored drops ofwater emerge from the bottom of the glacier.Most of the water flows downhill as runoff (above groundor underground), eventually returning to the seas asslightly salty water.