# CALCULATING WIND SPEED

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```					Our Atmosphere

CALCULATING WIND SPEED
Wind speed can be measured using an anemometer. A simple anemometer catches the wind. Depending on
how forceful the wind is the device may be calibrated.

Design your own device which will be used to measure wind speed. Use the information in the diagrams
below for ideas. For each of the devices consider how the wind is caught and how this is used to give
a measurement.

1. Revolving coffee cups                                           2. Swinging shoe box

lidded box such
hole                 foam cups                                          as a shoe box
glued onto plate
knitting needle
aluminium                                                          tape
pie plate
cardboard
test tube
long
nail                                                               viewing slot
wooden block
Calibrate the scale by experimenting and
Count the number of revolutions in a set time.                    comparing to the Beaufort scale.

wood (ruler)       thumb tack           spirit level (corked
3. Blowing ball                                                                                    test tube with air
bubble)
a.   Face the device into the main wind direction.
b.   Make sure the device is level.
c.   Take measurements over a two-minute period.           protractor
d.   Average minimum and maximum angle readings.
e.   Use the table below to find the wind speed.                  fishing line
ping pong ball

Angle     90º    85º   80º     75º   70º   65º    60º    55º     50º   45º   40º    35º

miles/h   0      5.8   8.2     10.1 11     13.4 14.9 16.4 18           19.6 21.4 23.4
km/h      0      9.3   13      16.3 19     21.1 24 26.4 29             31.5 34.4 37.6
m/sec     0      2.6   3.7     4.5 5.3     5.9 6.7 7.3 8.1             8.8 9.6 10.4

Name of device                   How is the wind caught?                      How is the wind measured?

1. Revolving coffee cups

2. Swinging shoe box

3. Blowing ball