Session 15 Construction of wind measuring poles

TOTAL TIME: 2 Hours

OBJECTIVES: To construct several wind measuring devices

To calibrate these devices

To discuss some of the variables regarding wind measurement

MATERIALS: 20 foot (7 meter) or longer light poles or bamboo, ball of red or brightly colored yarn, small beads or nuts of about the same weight, fastenings (nails, lashing material)

PROCEDURES:

Step 1: 5 minutes

Discuss difficulties involved in measuring the wind speed and frequency (daily and seasonal changes, height above ground, etc.)

Step 2: 20 minutes

Discuss ways to measure the wind velocities, anemometers, wet fingers, kites, effect on the trees and buildings, wind pole, bubbles.

Trainer Note

Have everyone become familiar with the Beaufort scale. During training have people guess the wind speed and then check it, using the Beaufort scale, in order to improve their estimation abilities.

Step 3: 5 minutes

Explain the construction of the wind measuring pole.

Step 4: 1 hour

Break up into construction groups. Each group should build a measuring pole. If poles are of significantly different lengths or are used at different elevations the resulting wind velocities can be compared.

Step 5: 30 minutes

Examine and "calibrate" each pole and then use them to measure wind speeds.

RESOURCES: Copies of Attachment 15-A
Anemometer of some type

Attachment 15-A
Construction of Wind Measuring Poles

THE BEAUFORT SCALE OF WIND SPEEDS

Beaufort No.	Description	Miles/Hour	Kilom/Hour	Effect
0	Calm	0	0	Still: smoke rises vertically
1	Light air	1-3	1-5	Smoke drifts
2	Light breeze	4-7	6-11	Wind felt on face, leaves rustle.
3	Gentle breeze	8-12	12-19	Leaves & small twigs move constantly, streamer extended.
4	Moderate breeze	13-18	20-29	Raises dust & papers moves twigs & thin branches.
5	Fresh breeze	19-24	30-38	Small trees in leaf begin to sway.
6	Strong wind	25-31	39-50	Large branches move, overhead, wires whistle, umbrellas hard to control.
7	Moderate gale	32-38	51-61	Whole trees move, offers some resistance to walker.
8	Fresh gale	39-46	62-74	Twigs break off trees, hard to walk.
9	Strong gale	47-54	75-86	Blows off roof shingles
10	Whole gale	55-63	87-100	Trees uprooted, much structural damage.
11	Storm	64-72	101-115	Widespread damage (rare inland)