Download Practical activities Wind speed

HOW TO MAKE AN ANEMOMETER TO MEASURE WIND SPEED
A. Introduction: You will learn how to make
and use an anemometer to determine
wind speed.
B. Materials
 2 plastic drinking straws
 Sticky tape
 Scissors
 4 small paper cups
 Straight pin
 Pencil with a new eraser
 Stapler
C. Procedure
1. Arrange two plastic drinking straws to form a cross and tape them together
at the centre.
2. Staple the top side of one drinking cup, to the end of each straw, so the open
ends of the cups all face the same direction.
3. Push a straight pin through the centre of the straws into an eraser on the
end of a pencil. This provides an axle.
4. Mark one of the cups; this will be the used for counting when the
anemometer spins.
5. Blow on the anemometer to ensure it spins easily.
Use a wind vane to measure wind direction
A. Materials
 Anemometer
 Stop watch
B. Procedure
1. Assign the following roles to the members of the group:
a. A ‘time keeper’ – responsible for timing one minute for each trial
b. A ‘counter’ – responsible for counting the rotations (others may
wish to count on their own, but the ‘counters’ readings will be the
ones recorded
c. A ‘holder’ – responsible to holding the anemometer while the spins
are counted; the ‘holder’ should hold the anemometer to ensure the
wind is unobstructed
2. Go outside. The ‘holder’ should hold the anemometer so it has full access to
the wind from all directions.
3. When the ‘time keeper’ says GO, the ‘counter’ will count how many times
the mark passes them in one minute. Record your result.
4. Repeat the above two steps (step 2 and 3) and record an average number of
spins.
5. Use the Beaufort Wind Scale to determine approximate wind speed.
Beaufort Wind Scale
Wind force Description
0
Calm
1
Light air
2
Light breeze
3
Gentle breeze
Wind speed (km/h)
0
1-5
6-11
12-19
4
20-28
Moderate breeze
Specifications
Smoke goes straight up
Wind motion visible in smoke
Wind felt on face; leaves rustle
Leaves and small twigs in
constant motion
Raises dust and loose paper;
5
6
7
8
9
10
Fresh breeze
Strong breeze
Near gale
Gale
Strong gale
Storm
29-39
40-50
51-61
62-74
75-88
89-102
11
12
Violent storm
Hurricane
102-117
118+
small branches moved
Small trees begin to sway
Large branches in motion
Whole trees in motion
Twigs break off trees
Slight structure damage
Trees uprooted; considerable
structural damage
Widespread structural damage
Massive and widespread
damage to structure
C. Results: In your journal, draw up a table to record your results.
D. Discussion: Provide an explanation for the results. In your journal answer the following:
 Explain how the anemometer works.
 Complete a statement, which states the results from your findings. Such as ‘On
May 31, 2011 at 10.00 am, it was blowing a gentle breeze and the wind speed was
approximately 12-19km/h.’
 You can multiply the average number of spins by 60 to determine how many times
the anemometer would spin in an hour. In your journal complete a statement,
which states how many times your anemometer spins per hour.
Sample data table
Date
Time Number of spins (/minute)
May 31,
2011
10.00
am
32
40
26
30
Average
number
of spins
(/min)
32
Beaufort Wind
Scale
Description
Wind
speed
(km/h)
Gentle breeze
12-19