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Introducing the newest Hydrospheric and Biospheric Sciences Laboratory Lithograph, "The
Water Cycle". This lithograph was created as part of a huge demand for NASA
water cycle information. The lithograph serves as a science resource for the
science-attentive public, educators, students, and science research professionals.
The Water Cycle Lithograph was a collaboration of B.
Campbell, R. Kelly, D. Belvedere,
from NASA's Goddard Space Flight Center, and C. A. Schlosser from MIT.
Click here to download the print-ready PDF (Portable Document Format) of the Water Cycle Lithograph.
If needed, Adobe's Acrobat Reader is freely available by
clicking here.
Precipitation, evaporation, and condensation are all terms that
sound familiar, yet may not mean much to you. They are all part of the water cycle,
a complex process that not only gives us water to drink, fish to eat, but also
weather patterns that help grow our crops.
Water is an integral part of life on this planet and that is why NASA plays
a major role at the forefront of water cycle research. Currently, there are
many NASA missions that are simultaneously measuring a myriad of
Earth’s water cycle variables; Evaporation, Condensation, Precipitation,
Groundwater Flow, and Runoff. NASA’s water cycle research missions can
be grouped into 3 major categories; Water Cycle, Energy Cycle, and Water
and Energy Cycle Missions. By studying each and every variable of Earth’s
water and energy cycles, “As Only NASA Can”, a crucial understanding
of the water cycle’s effect on global climate is currently underway.
The Earth was formed approximately 4.6 billion years ago. During this
formation, gases (water vapor and carbon dioxide) trapped in Earth’s core
were released by volcanoes, creating the atmosphere. About 800 million
years later (3.8 billion years ago), oceans were formed on this planet. Once
the Earth cooled enough for the water vapor to become liquid, the water
vapor fell as rain, forming the oceans. Once the oceans were formed, the
Sun’s energy became the driving force of the water cycle. Over Earth’s
history, the oceans and continents have undergone great transformation,
primarily due to an evolving water cycle. Since the evolving water cycle has
an impact on everything from environmental concerns to human water
demands, NASA realizes the crucial need for understanding all the impacting
variables of the water cycle.
Only about 3% of Earth’s water is salt-free,
or fresh. Two percent of the
Earth’s water (about 66% of all fresh water) is in solid form, found in ice
caps and glaciers. Because it is frozen, the fresh water in ice caps is not
available for use by people or plants. That leaves about 1% of all the Earth’s
water in a form useable to humans and land animals. This fresh water is
found in lakes, rivers, streams, ponds, and in the ground. It is also found
in the atmosphere in liquid, solid and vapor form. Did you know that if
you live in the United States, there are 40 trillion gallons (1.51416x1014
liters) of water above your head on an average day? Some of the water that
falls to Earth soaks into the ground and provides runoff to rivers, lakes,
and oceans. The remainder, more than 2.5 trillion gallons (9.4635x1013
liters), returns to the atmosphere through evaporation, and the cycle begins
again.
The water cycle is a never-ending global process of water circulation
from clouds to land, to the ocean, and back to the clouds. To give an idea of
how fast or slow water moves through the global system, in the oceans,
water takes about 3000 year to completely cycle through. For ice caps and
glaciers, it may take up to 15,000 years while for the atmosphere it usually
takes a few days. In rivers, the turnover is also a few days to weeks but
groundwater flow can take hundreds to thousands of years.
To put some real numbers
to this cycle, in the atmosphere, rivers, oceans,
groundwater, and elsewhere on Earth there is a total of 326 million cubic
miles of water (more than 326,000,000 trillion gallons [1.234x1015 liters]).
Less than one percent of that total is our supply of drinking water.
Recent estimates have put the global water demand at 800 cubic miles of
water per year, or approximately 800 million Olympic-sized swimming
pools per year!
Through NASA’s water cycle research, we can understand how water
moves through the Earth system in the hydrological cycle and we will be
in a better position to effectively manage this vital renewable resource and
help match the natural supply of water with human demands. NASA is the
only national agency that has the ability to support a full range of water
cycle research, from large-scale remote sensing to in-situ field observations,
data acquisition and analysis, and prediction system development.
Create Your Own Water Cycle Model
Introduction
On the Earth, water maintains
a constant cycle of change and motion.
This cycle, known as the Water Cycle or Hydrologic Cycle contains five
major processes: evaporation, condensation, precipitation, groundwater
flow, and surface runoff. This activity will allow the teacher and/or
students to create their own working model of the water cycle using
common materials found in a science classroom.
Materials
Aquarium or clear rectangular shoe/storage box; plastic wrap; modeling
clay; desktop lamp; water (representing an ocean); ice cubes (whole or
crushed).
Procedure
- Previous to setting up the experiment, discuss with students the
five major stages of the water cycle. As an extension to instruction,
if classroom Internet access is available, please visit
http://watercycle.gsfc.nasa.gov/ to
download and discuss the “Water Cycle Movie”.
- Begin the construction of your “Water Cycle Model”
- Mold the modeling clay into the shape of a mountain with a vertical
side and a sloping side.
- Place the clay mountain into the left side of the aquarium with the
sloping side facing the interior of the aquarium where the majority of
the “ocean” will be.
- Pour water into the aquarium until approximately 1/4 of the mountain
slope is covered.
- Cover the top of the container with the plastic wrap, then place several
ice cubes on plastic wrap directly above the clay mountain.
- Position the lamp over the ice cubes and turn the lamp on. Please be
careful, as the lamp will get extremely hot due to the time duration of
this experiment.
- Keep the lamp on for approximately 15-25 minutes (dependent upon
size of bulb) and have students observe any changes occurring in the
aquarium environment that are water cycle related.
Questions
- Which of the 5 stages of the water cycle were you able to observe in
this experiment?
- What is the energy source in this experiment and what does it represent?
- Was evapotranspiration demonstrated in this experiment? If yes,
where? If no, how could we have demonstrated it?
- Where in this experiment does condensation occur more rapidly?
How do you know?
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