Activity

1. Discuss how winds are formed in nature and how friction can cause winds to slow down near the ground.
2. Use the tissue paper to create a wind strip that will show the movement of wind.
3. To do this, carefully cut the tissue paper into strips 1 cm wide and 30 cm long.
4. Tape the strips to the edge of a wooden stick.
5. Set the fan at the end of your table and switch it on low to simulate a light breeze.
6. Raise the wind strip one meter from the fan and make note of the height of the windstrip.
7. Record how high the wind elevates the strips.
8. Use the railroad board and bricks to form a "valley."
9. Stand the bricks in pairs and lean the railroad board against the bricks.
10. Place the fan at the large end of the funnel.
11. Hold the wind strip at the small opening of the "valley" at the same height as in step 5.
12. Turn on the fan (low setting).
13. Measure the movement of the strips. How high do they rise? Do the strips show that the valley's shape has changed the character of the winds?
14. Record you observations.
15. Read the description of anabastic winds (below). How does this process relate to your experiment?
16. Increase the setting and observe the change in the wind.
17. Record your observations.

Assessment Ideas

• Have the students construct models of both anabastic and katabastic wind flow. Use a large sheet of butcher paper to design a model of each of the wind types. Label the wind direction using arrows.
• Use your observations to construct a graph that illustrates the data collected at each fan setting.
• Use a computer graphing program to make final charts.
• Devise a plan to illustrate the difference in wind flow as the settings are increased and decreased.