Linda F. Malanson
Many people need to find out what the wind conditions are each day. Aircraft crews need to know the strength and direction of the wind on takeoff and landing. Winds make waves at sea, so sailors need to know what conditions to expect.
The direction from which the wind blows is measured with a wind vane. Speed is measured with an instrument called an anemometer. In weather forecasts, wind speed is usually reported in miles or kilometers per hour, or—for ships and aircraft—in knots. One knot is equal to 1.85 km/h (1.15 mph). The Beaufort Wind Scale gives wind speed as a “force”.
The Beaufort Wind Scale originally described the type and amount of sail a ship should carry in particular winds. Today the scale describes the effects seen on land and relates these to wind speeds. Look for the signs it describes and you can estimate the wind speed. The Beaufort Wind Scale is as follows:
Force 0
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Smoke rises vertically, and the air feels still.
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Force 1
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Rising smoke drifts, but wind vanes and flags do not move.
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Force 2
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Smoke shows the wind direction.
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Force 3
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Flags, leaves, and twigs move gently.
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Force 4
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Loose pieces of paper blow about.
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Force 5
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Small leafy trees sway in the wind.
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Force 6
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Umbrellas are difficult to use.
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Force 7
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Pressure is felt when walking into the wind.
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Force 8
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Twigs are torn from trees.
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Force 9
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Slates and chimneys are blown away.
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Force 10
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Trees are broken or uprooted.
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Force 11
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Cars overturned. Trees blown a distance.
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Force 12
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Widespread devastation. Many trees uprooted. Buildings destroyed.
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(figure available in print form)