Warm Earth,
Hot EaArth
Summary: Create models of how the change in the Earth’s overall temperature impacts the
water cycle, our climate, and even local weather.
Materials:
● Sources of warm (bath water temperature) and hot (tea or coffee temperature) water. A
coffee or tea pot works great.
● Two quart size sealable plastic bags (such as Zip-lock)
● Two 8 to 12 oz. styrofoam cups (Each must sit upright
inside a sealed plastic bag)
Engagement: Have you, your parents, or grandparents noticed
a change in the weather where you live? Have there been any
extremely large rain, snow, or wind storms? Or perhaps your
area has had unusual drought? This activity illustrates why
these events occur.
Exploration or Procedure:
● Heat water. Mix some of the hot water with cold water to
create a source of warm water as well. Record the
temperatures of the water.
● Label one cup “Hot EaArth” and one cup “Warm Earth.”
Optional: Add first names of your grandparents or great
grandparents to the “Warm Earth” cup. Add names of
your friends, children, or grandchildren to the “Hot
EaArth” cup.
● Fill the Warm Earth cup two thirds full of warm water,
carefully place inside one of the ziplock bags, and seal it. Repeat with the Hot EaArth
cup and hot water. CAUTION: Be very careful with the hot water. If doing this activity
with young children, an adult should handle the hot water portion of this activity.
● Wait about five minutes, occasionally observing what is happening in the two models.
During this time you may draw the water cycle. Review vocabulary (evaporation,
condensation, precipitation) and emphasize that energy is required to evaporate water.
● Record the appearance of the two bags. This may be done with a drawing as well as a
written description. If possible, take photos of the two bags with the cups still inside.
● Carefully remove the cups without spilling or wetting your hand/fingers with the moisture
inside the bag. Partially close the bags. Hold the top of a bag with one hand and place
two fingers of the other hand on each side of the bag, also near the top. Pull the bag up,
so the moisture collects at the bottom. Repeat for the second bag.
●
Compare the amount of water in the hot vs. warm model. If you have a pipet or
graduated cylinder, you may measure these.
Explanation:
● Which bag contained the most water, the warm or the hot? Why?
● What kind of precipitation occurs when it is too cold to rain?
● If you did not understand the water cycle, would you expect a warmer Earth to result in
larger snowstorms? How can you explain this?
Elaboration:
● What do the larger drops on the Hot Earth system represent? Does this model predict
more rain storms, or storms with larger amounts of rainfall?
● What do the different amounts of water in the bags represent? Can we expect more
floods on a hotter Earth, or larger floods?
● What you can’t see is also important. The same amount of energy needed to evaporate
the water in the cups was released when the water condensed on the side of the bag. In
the Earth’s water cycle this energy is released when water condenses into clouds. The
changes in temperature and pressure produce wind. Does this model predict more
windy days, or storms with very high winds?
● What evidence supports our argument that the Earth is warmer? Below is a graph of
annual average global surface temperatures. Temperatures fluctuate, but what do you
see as the general trend? How long has this trend been occurring?
● Actual
data for the
Earth’s
●
temperature can be obtained from the My NASA Data Live Access Server. The URL is
given in the resources section below. How has the temperature changed at your
latitude?
What has caused the Earth to warm up? Is this part of a natural cycle? What about Ice
Ages? We’ll cover these concepts in future lessons.
Evaluation:
1. What is the energy source for the Earth’s water cycle? ________________________
2. Which part of the water cycle requires energy, evaporation or condensation?
3. Which part of the water cycle releases energy, evaporation or condensation?
4. About how much has the Earth warmed during the last ten years? _______________
5. True or false? A warmer Earth can result in snowstorms with greater snowfall.
Resources:
● Additional NASA graph of temperatures from:
http://climate.nasa.gov/climate_resource_center/23.
● My NASA Data for global temperatures is at:
http://mynasadata.larc.nasa.gov/las/UI.vm#panelHeaderHidden=false;differences=false;
autoContour=false;xCATID=4C3629220F9706C2D4804AB425B825D3;xDSID=surface_
conditions;varid=aux_skint_mon-idbdc7e55e97;imageSize=auto;over=xy;compute=Nonetoken;tlo=15-Mar-2000;thi=15Mar2000;catid=4C3629220F9706C2D4804AB425B825D3;dsid=surface_conditions;varid=au
x_skint_mon-id-bdc7e55e97;avarcount=0;xlo=0;xhi=360;ylo=90;yhi=90;operation_id=Plot_2D_XY_zoom;view=xy
● Additional fabulous resources for energy education materials are at:
www.uni.edu/ceee/free.