Collins Big Cat — WIND POWER: Band 13/Topaz

Wind Power Wind power is used more and more around the world WIND POWER

to give us electricity in our homes. But what is wind? How can it be used to make electricity and why

Wind Power

is it replacing other forms of energy?

Find out in this book.

Browse the complete Collins catalogue at

www.collins.co.uk

An information book

ISBN 978-0-00-820880-6

9 780008 208806 www.collins.co.uk/collinsbigcat

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Collins Big Cat Inform is a large range of topical non-ďŹ ction to support the curriculum.

Emily Dodd 26/01/2017 15:31

What is wind?

Wind is moving air.

We can’t see the wind but we can see and feel the effects of the wind ass it blows things around.

Wind is created by differences in air temperature. ature.

The sun heats up the land d and, as the land gets warmer, the air above the land warms up too. Warm air rises and colder air moves below it. This flow of moving air is wind. The bigger the difference in air temperature, the faster the air moves and the stronger the wind blows.

cool

warm

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Some parts of the world have a summer monsoon every year.

Monsoons are air currents that bring cool wet air from the oceans to the warmer land, which causes rain storms.

Fact A flow of moving air is called a current.

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Measuring wind Wind speed is measured with an instrument called an anemometer.

The little cups catch the wind, and the anemometer measures

an anemometer

how fast they spin around. Wind speed d can be measured in metres per second, kilometres per hour, miles per hour, knots, gale force, and on the Beaufort scale.

The Beaufort scale uses observation to work out wind speed. We can observe wind direction too, by looking at where the smoke from a chimney blows or which way a flag flaps in the wind. Try dropping something light like a feather outside and watch which direction it moves.

Windsocks are used at airports to show pilots the direction of the wind as they come in to land.

The wind blows through the sock, and the smaller end points to where the wind is blowing towards.

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Beaufort scale number and description

Wind speed Km/h

Observation

0 calm

0–2

smoke rises vertically

1 light air

2–5

smoke drifts slowly

2 light breeze

6–12

leaves rustle

3 gentle breeze

13–20

leaves and twigs in motion

4 moderate breeze

21–29

small branches move

5 fresh breeze

30–39

small trees sway

6 strong breeze

40–50

large branches sway

7 moderate gale

51–61

whole trees in motion

8 fresh gale

62–74

twigs break off trees

9 strong gale

75–87

branches break

10 whole gale

88–101 trees snap and are blown down

11 storm

102–115 widespread damage

12 hurricane force

116–130 extreme damage

Wind direction can also be measured using a weather vane, a decorative instrument that points to where the wind is coming from.

When we measure wind direction, we say where the wind has come from, not where it’s going to. For example, if the wind is blowing from the north to the south, we call it a northerly wind.

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Wind turbines If the wind is travelling at least 12 km/hr, then it’s strong enough to push the blades of a wind turbine around and we can use it to make electricity. If the wind speed reaches over 88 km/hr the turbine can’t operate.

The blades of a wind turbine are mounted on a tower and there are sensors to monitor wind direction and wind speed.

wind

nose cone

anemometer weather vane

blades

pylons generator

electricity

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substation transformer

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