Name ________________________________________ Date _________ Period _____
MESO
Thunderstorms Module
The Ups and Downs of Hail
Objective:
Demonstrate the ability of the wind to suspend rain and hail in clouds.
Overview:
You will suspend a ping pong ball in the stream of air supplied by a hair dryer or fan,
simulating how hail is supported in thunderstorms. Some preliminary discussion of the
following concepts with your teacher will be useful: gravity, air resistance, and terminal
velocity.
Supplies:
 Hand held hair dryer or portable fan that can be pointed straight up
 Ping pong ball
Procedure:
1. Start off using the hair dryer or fan to create a vertical stream of air pointing
toward the ceiling.
2. Have your partner place the ping pong ball into the stream of air
3. How does your ping-pong ball respond?
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For the remaining questions, use the following table containing values for the
terminal fall speeds of various objects.
object
ping pong ball
baseball
rain drop
rain drop
hailstone
hailstone
hailstone
hailstone
diameter
roughly 4 cm (1.6 in)
roughly 7.5 cm (3 in)
0.1 cm (0.04 in)
0.5 cm (0.2 in)
2.5 cm (1 in)
5 cm (2 in)
7.5 cm (3 in)
10 cm (4 in)
fallspeed
9 m/s
42 m/s
4 m/s
9 m/s
19 m/s
34 m/s
46 m/s
56 m/s
4. What is the speed of the air at the height where your ping pong ball hovers?
5. What other object in the table could hover at roughly the same position?
6. Could a hailstone with the same size as a ping pong ball hover in your airstream?
7. What would happen to a small (0.1 cm) rain drop in your airstream?
8. Why don’t baseballs and baseball-sized (7.5 cm) hailstones fall at exactly the
same speeds?
9. The world’s largest hailstone on record had a diameter of 17 cm (6.7 in).
Estimate how fast that record hailstone would fall.
10. What do your results tell you about the air motions in thunderstorms? How is it
that hail can grow to be so large?
11. Which kind of hailstones (large or small) will have the most time to melt as they
fall to the ground?