HEAT TRANSFER IN THE ATMOSPHERE, OR
CONDUCTION, CONVECTION, RADIATION, OR
WHY DOES HOT AIR GO UP?

ACTIVITY INTRODUCTION/EXPECTATIONS
Upon completion of this activity, you should know or understand:

• How heat is transferred by conduction, convection, and radiation.
• Why hot, dry air is pushed upward by cool or moist air.
• How thermals can help produce instability in the atmosphere
• How the convective process in the atmosphere builds clouds and strong convection builds hail.
• How thermals or convective cells are beneficial.
• How to construct a hot air balloon from tissue wrapping paper.
• How to safely launch your hot air balloon.

ACTIVITY DESCRIPTION
In this activity, you will be divided into groups of at least 3, but no more than 4. Construction of a tissue balloon is fun, launching them is more fun, but do not loose focus that we are studying heat transfer in the atmosphere. Remember, the faster and farther the air rises in the atmosphere, the greater chance we have of hail and possible severe weather.

MATERIALS

• 9 pieces of tissue wrapping paper
• 1 glue stick
• 1 piece of wire about 18 inches long

METHODS/PROCEDURES
*Note: small overlaps and less glue make a larger, lighter balloon!

1. Follow the steps from the power point presentation on building a hot air balloon.
2. Launch the balloon by carefully slipping the wire opening of the balloon over the stove pipe on the camp stove. Make certain you and your partners keep the balloon from overlapping the vent pipe opening. The balloon fills with the hot air by convection under and through the pipe and coming out the top, so in a way, the balloon becomes its own little convection cell.

RESULTS/CONCLUSIONS

1. Did your balloon go upward? Estimate how high and how long it was in the air.

2. What forced the balloon upward?

3. How is convection important in the production of hail?

4. Give an example of how each were used in the launching of your balloon:

a. Conduction

b. Convection

c. Radiation

5. What part of the United States generally gets the most hail?

6. What part of the year do most hail storms form? Why?

7. Would you expect most hail storms to happen in the morning or evening? Why?

8. Briefly explain the process by which a hail stone grows larger.

9. Did any of the balloons get caught in an atmospheric thermal?
What happened if it did? If not, what do you expect would have happened?

10. Explain why some balloons seemed to go higher and farther than others.