TITLE:     THE CLOUD IN THE BOTTLE

AUTHOR:   Michael Kneese; Snake River Jr. High, Idaho  

GRADE LEVEL/SUBJECT:   Appropriate for grades 4-12

OVERVIEW:  Students are somewhat interested in the weather
and can be made increasingly aware of cloud formation by
this rather simple in class demonstration.

PURPOSE:  The purpose to this activity is to demonstrate to
the students the direct affects of pressure and temperature
on cloud formation.

OBJECTIVES:
       1.  To demonstrate the principles involved in cloud formation.

       2.  Transfer this information to weather maps to
predict cloud formation and clearing.

       3.  Introduce the term nuclei, necessary for 
attachment to form clouds

RESOURCES/MATERIALS:  
     1.  Wide mouth gallon pickle jar

     2.  Heavy duty clear plastic bag

     3.  Rubber bands or masking tape

ACTIVITIES AND PROCEDURES:
     1.  Place about 20 ml of water in a wide mouth gallon pickle jar

     2.  Place a lit match into the jar.

     3.  Quickly place a heavy duty clear plastic bag over the mouth
of the jar and secure a firm seal by placing a rubber band/masking
tape around the top of the jar.

     4.  Push the bag into the jar quickly, then pull the bag out. Observe!

TYING IT ALL TOGETHER:  This activity illustrates how humidity,
temperature, and air pressure influence the formation of clouds.
The water produces high humidity in the jar and the smoke introduced
by the match provides nuclei on which the water vapor can condense.
As the bag is pushed into the jar pressure and temperature in the
jar 
increases causing the jar to clear.  Upon pulling the bag out,
pressure and temperature decrease allowing water vapor to condense
and produce a "cloud" inside the jar.


Questions for further inquiry:
      Why are smoke and water added to the jar? (provide moisture
and nuclei for cloud formation)

      What does pushing and pulling on the bag do to the jar?
(increases/decreases pressure)

      How would warming or cooling the jar effect the observations?
(decrease/increase cloud information)

      Relate your findings to weather conditions necessary to produce
cloudy/clear skies.