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The Process
Surface water is evaporated from
the earth by the energy of the sun. The water vapor forms clouds in the sky.
Depending on the temperature and weather conditions, the water vapor
condenses and falls to the earth as different types of precipitation. Some
precipitation runs from high areas to low areas on the earth's surface. This
is known as surface runoff. Other precipitation seeps into the ground and is
stored as groundwater.
Groundwater is water that fills
the spaces between rocks and soil particles underground, in much the same
way as water fills a sponge. Groundwater begins as precipitation and soaks
into the ground where it is stored in underground geological water systems
called aquifers. Sometimes groundwater feeds springs, lakes, and other
surface waters or is drawn out of the ground by humans. The water then can
evaporate, form clouds, and return to the earth to begin the cycle over
again.
Sunshine
The sun shines on water in rivers, lakes,
streams, wetlands and oceans and makes the water warmer. This turns the water
into vapor or steam. The water vapor leaves the lake or ocean or river and
goes into the air, where it becomes a cloud.
Evaporation
Evaporation is when the sun heats up water in
rivers or lakes or the ocean and turns it into vapor or steam. The water vapor
or steam leaves the river or lake or ocean and goes into the air, where it
becomes a cloud
Rain
When the temperature is warm, like during the
spring or summer, clouds get so full of water that rain starts to fall. The
rain falls onto the land and runs into streams and rivers. The water in the
streams and rivers runs into lakes and finally into the ocean. Some of the
rain that falls soaks into the ground and stays there until plants drink it or
until it goes deep enough into the ground that it is called "groundwater" and
goes to people's wells.
Snow
Snow is just like rain except it falls when the
air is cold, like during late fall and winter. Snow usually stays on top of
the ground until it melts, then it turns into water and runs into streams and
rivers. Some of the water from melted snow also goes into the ground for
plants and people to drink.
Mountains and Ice
Some of the snow that falls onto mountains
stays there a long time because it is so cold most of the time at the top of
mountains. This snow turns into ice and sometimes becomes glaciers. Snow and
ice on the top of mountains can stay there sometimes for hundreds of years
before it finally melts and runs into the streams and rivers.
Rivers and Streams
Rivers and streams carry the water that comes
from rain and melted snow into the ocean. They sometimes can carry this water
a long way. The Mississippi River in the middle of the United States carries
rain and melted snow from Minnesota and Canada all the way to the Gulf of
Mexico. When the weather is warm, sometimes the sun makes the rivers and
streams warm, some of the water turns into steam or vapor, and it leaves the
river and goes into the air where it becomes a cloud.
Oceans
Oceans are like really big lakes. Rivers and
streams carry all of the water that comes from rain and melted snow into the
oceans. When water gets into the oceans, it mixes and becomes salty. When the
sun shines on the oceans, the water gets warmer and becomes vapor, which goes
into the air and becomes a cloud. Most of the water on the earth is in the
oceans.
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Carbon Dioxide, Smoke, Sulfur
Water is sometimes known as the universal
solvent. It has a tendency to dissolve a little bit of everything it
touches. Dust, smoke from industry, carbon dioxide, spores and smog may be
absorbed by water droplets. |
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Acid Rain
For example, if it dissolves sulfur from
industrial smokestacks, it can form acid rain. This increases its capacity
to dissolve other substances. The water vapor in clouds eventually condenses
and falls back to earth as rain, sleet, hail or snow. |
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Calcium, Hydrogen Sulfide, Iron, Magnesium, Sodium, Radioactivity
As water runs over the surface it can become
cloudy, even muddy. Then, as water seeps down through the ground, it may
dissolve a little bit of the minerals and other substances that could be
present. |
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Odor, TCE, PCB, Trihalomethanes
By the time water returns to rivers, lakes or
underground aquifers, it may have accumulated amounts of the elements it has
contacted. |
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Fungicides, Herbicides, Insecticides
Along the way bacteria, chemicals,
agricultural byproducts, fertilizers, insecticides and other man-made wastes
may also enter the water. Even after reaching a home, it can continue to
dissolve materials such as lead from solder in plumbing pipes |
Did you know...?
- 97% of the water on
earth is in the oceans
- Only 3% of the water
on earth is freshwater
- About 2.4% of the
water on earth is permanently frozen in glaciers and at the polar ice
caps
- About 1/2 of 1 % of
the water on earth is groundwater
- Only about 1/100 of 1%
of the water on earth is in the rivers and lakes
- It takes 39,090
gallons of water to make a new car, including the tires
- Over 17,000,000 houses
use private wells for their drinking water supply
- A person can live
about a month without food, but can live only about 1 week without
water
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