CREATING A CLOUD

KEY CONCEPTS

  1. Clouds are visible masses of water particles in the air.
  2. Clouds are collections of tiny water droplets that form around particles of dust, dirt, salt, or other types of condensation nuclei.
 

MATERIALS

  • piece of chalk
  • newspaper
  • hammer
  • nail
  • medium-sized jelly or pickle jar
  • 2 lids: one that fits the jar, and one that is extra large so that it is able to rest on top of the jar
  • hot tap water
  • timer (watch, clock, etc.)
  • 2 ice cubes
 
 

PROCEDURE

  
 
 

Activity

  1. Place the piece of chalk on the newspaper.
  2. Hit the chalk with the hammer to make fine, powdery chalk dust.
  3. Set the chalk dust aside (note: try not to breath in the dust).
  4. Use the hammer and nail to punch holes in the extra-large jar lid. The holes should cover the entire lid.
  5. Fill the jar with the hot tap water
  6. Cover it with the lid that fits. Let the jar stand for 2 minutes.
  7. Remove the lid and pour out about 90% of the water (make your best estimate).
  8. Place the extra-large lid with the holes in it on top of the jar.
  9. Put the ice cubes on top of the lid. Let the jar stand for about 3 minutes.
  10. Remove the ice cubes and the extra-large lid.
  11. Sprinkle a pinch of chalk dust into the jar. Cover the jar tightly with the lid that fits.
  12. Observe the inside of the jar after about 2 minutes. A cloud has formed.
  13. Answer the following questions. How were the water droplets formed? How did the chalk dust help to form the cloud?
 
 

Assessment Ideas

  • Why is the dust such a necessary ingredient to the visibility of the water molecules? Why doesnąt it rain continually when there are clouds? Do some research to find out why the water droplets stick to condensation nuclei (tiny particles of dust, salt, etc.).
 
 
 

CROSS-CURRICULAR IDEAS

  • Geography: Have the students look at a weather map of the United States of America. Locate the major regions of cloud cover and rainfall. Why is there so much cloud cover in one area, yet completely dry in other areas? Remember, warm air holds more water than cold air (that is, water will condense out of cold air; water vapor will remain in warm air). Continue the exercise and use a world map. The globe is zoned into a number of climate regions. Why is the equatorial region covered with clouds an rainfall? Why are the polar regions dry and clear?
  • Photography: Photograph the clouds. Learn to differentiate between cirrus clouds (feathery wisps, curls, or ringlets, high in the sky). These clouds often mean fair skies. Altocumulus clouds (fluffy, heaped-up masses of clouds mid-level in the atmosphere). These clouds may mean changing weather. Nimbus clouds (low, dark-gray clouds, full of water). These clouds generally mean rain or snow. Stratus clouds (calm, flat layers of clouds that spread out a low level). These clouds may mean an overcast dry day or approaching rain or snow. Cumulus clouds (puffy and bunched-up clouds at a low level). These clouds often mean fair weather. Create a portfolio of the images of the clouds with descriptions and consequences of each of them.
 
 

VOCABULARY

  • condense: turn or change to a liquid (for example, change from a vapor to a liquid); usually from cooling (molecules compact together).
  • evaporate: turn or change to vapor (for example, change from a liquid to a vapor); usually from heat (molecules expand).
  • nucleus: central part, or core (plural: nuclei).
  • vapor: gaseous phase of a solid or liquid.
  • visible: what we see.
 
 

SOURCE

  • "Winds of Change" educational CD-ROM, Copyright Caltech and NASA/Jet Propulsion Laboratory