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WORKSHEET 16

Activity - Measuring Wind Speed

Print and copy this worksheet for use in the classroom.

 
 

Purpose

To measure wind speed and realise that it can be done with minimal equipment and surprising accuracy.

Equipment

  • strong thread or thin fishing line - about 40 cm long
  • ping-pong ball
  • large protractor
  • glue and tape
  • thick cardboard (for mounting protractor)

 
 

Procedure

  1. Mount the protractor with tape to the cardboard, curved side pointing down.
  2. Tape or glue the thread to the ping-pong ball.
  3. Tie or glue the other end of the thread to the center of the protractor.
  4. When the wind blows the thread off center, read the angle on the protractor
  5. Convert this angle to the wind velocity in this table.
  6. Use your instrument outside and away from buildings to measure wind speed. At the same time, use the Beaufort wind scale to write down your observations about the strength of the wind.
String Angle (degrees)
90
80
70
60
50
40
30
20
Wind Speed (km/h)
0
13
19
24
29
34
41
52

 

Questions

Answer the following questions in the spaces provided.

 

 
  1. What is wind?







  2. Can wind be useful to us?








  3. What damage can wind do?







  4. Does your instrument give a measurement of wind speed that agrees with the measurement using your observations and the Beaufort wind scale? Can you suggest any improvements to the instrument?

 

Beaufort Wind Scale
 
Beaufort Number
 Description Wind Speed (km/h) Effect
0
 Calm Less than 2 Smoke Rises Vertically
1
 Light Air 2-5 Smoke drift shows wind direction, wind vanes don't move.
2
 Light Breeze 6-12 Wind felt on face, wind vanes move.
3
 Gentle Breeze 13-20 Leaves and small twigs in motion, hair disturbed, clothing flaps.
4
 Moderate Breeze 21-30 Dust and loose paper moved, small branches move.
5
 Fresh Breeze 31-40 Small trees with leaves begin to sway, wind force felt on body.
6
 Strong Breeze 41-51 Large branches move, umbrellas difficult to use, difficult to walk steady.
7
 Moderate Gale 52-63 Whole trees in motion, inconvenience felt when walking.
8
 Gale 64-77 Twigs broken off trees, difficult to walk.
9
 Strong Gale 78-86 People blown over, slight structural damage including tiles being blown off houses.
10
 Whole Gale 88-101 Trees uprooted, considerable structural damage.
11
 Storm 102-120 Widespread damage.
12
 Hurricane Greater than 120 Widespread devastation.
 


Explanation
 

Heat from the sun warms the air and makes it rise. This occurs mainly in tropical regions, near the equator, where the sun's energy is most intense. As warm air rises, cool air rushes in to take its place. We feel this movement of air as wind.

During the day in summer, land is generally warmer than the sea. This temperature difference can set up cooling daytime sea breezes, which can penetrate many kilometres inland. At night, breezes may blow in the opposite direction, from the land to the sea.

Similar daily changes in temperature occur over irregular terrain and cause mountain and valley breezes. Other winds induced by local phenomena include whirlwinds and winds associated with thunderstorms.

 


Extension Activity

  Can you devise another simple instrument for measuring wind speed?
 


Fact File

 

The strongest wind ever reliably measured on the surface of the Earth was 362 km/hr, recorded on Mt. Washington in the United States on 12 April, 1934. Much stronger winds, however, occur near the center of tropical cyclones.

This activity is courtesy of
the Cooperative Research Center for Southern Hemisphere Meteorology



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