Weather Unit

Lesson 8 - Measuring the Wind

WindWhat do you know about wind? What can wind do? Does wind always blow at the same speed and in the same direction?

Think about the tools you have seen so far that measure weather conditions. Can a thermometer measure the wind?

What is Wind?

Wind is simply air in motion.

Wind is caused by the way the sun warms the earth. Some parts of the earth get direct sun rays and that makes them warmer.

Other parts of the earth get indirect rays and are cooler.

Warm air is lighter than the cool air. Therefore, the warmer lighter air rises. As it rises, it gets replaced by cooler air.

This movement of the warm and cool air causes wind.

We may not be able to see the wind, but we can certainly feel it.

We also know that the two main gases that make up wind are oxygen and nitrogen.

Meteorologists use tools to help us understand wind direction and speed.

Weather vanes, as well as flags and windsocks, are used to tell the direction the wind blows.

It may look like an ice cream scoop from outer space, but an anemometer is used to measure the speed of wind.

Depending on where you live, wind speed is measure in miles or kilometers per hour.

Why do we need to measure wind?

Knowing about wind direction and wind speed is important to many people for many reasons. Sailors, for example, need to be aware of wind direction and speed when they are out at sea.

Long ago, most ships had sails. Big sailing ships traveled from one place to another using only wind power. Sailors needed to know all about wind direction and speed so they could steer their ships where they wanted to go. Some ships still use wind power today, even if they have other ways of moving.

Sir Francis Beaufort

In early 1800’s, an admiral in the British Royal Navy named Sir Francis Beaufort learned how important it was for sailors to observe the weather. He Knew that observing weather could help them predict the weather.

Beaufort began keeping a notebook in which he wrote weather observations every day. When he was 30 years old, he developed a measuring scale to help sailors record wind strength consistency.

• At first , sailors used Beaufort’s scale as they watched the wind move ocean waves. They compared the movement of the waves to the scale to tell how fast or strong the wind was blowing. The information helped them know which sails to raise on their ships.

• Today people use Beaufort’s scale to measure wind conditions on land, too. You can look at a flag or wind sock and estimate how fast or strong the wind is blowing.

The Beaufort Scale is a measure for the intensity of the wind based on conditions. It can be used to estimate wind speed.

The Beaufort scale is divided into a series of values, from 0 for calm winds to 12 and above for hurricanes.

Beaufort scale

smoke rises vertically

trees uprooted

Can you describe for the Beaufort Scale? Two examples have been done for you.

Beaufort Scale

Effects Speed (kph)

0 Smoke rises vertically 0

1 Smoke drifts 1-5

2 Wind felt on face, leaves rustle 6-11

3 Leaves and small twigs move 12-20

4 Small branches move 21-30

5 Small trees sway 31-40

6 Large branches sway, umbrella used with difficulty 41-50

7 Whole trees sway 51-60

8 Twigs break off trees, hard to walk into wind 61-74

9 Chimney pots and slates blow off 75-87

10 Trees uprooted 85-100

11 Rarely occurs inland 101-115

12 Disastrous, widespread damage 115+

Beaufort scale

Beaufort scale

Glue your Beaufort Scale in your science journal.

Watch this short clip on the Beaufort Scalehttp://www.learningliftoff.com/wp-content/uploads/2014/07/beaufort_scale.swf

This video shows land and waterhttps://www.youtube.com/watch?v=f-VVOM_DYdo

Depending on its strength, we refer to wind as a gentle breeze, gale force winds or even a tornado.

How do Tornados form?

Watch this video on how tornados form

https://www.youtube.com/watch?v=lmWh9jV_1ac

We have strong winds on Earth but the fastest planetary winds are on Saturn and Neptune. To see them, you’ll need a good travel agent.

Videos

Weather tool video and picture

http://studyjams.scholastic.com/studyjams/jams/science/weather-and-climate/weather-instruments.htm

Air Pressure and Wind Video

http://studyjams.scholastic.com/studyjams/jams/science/weather-and-climate/air-pressure-and-wind.htm

For more Presentationscheck out these links on phillipmartin.info and pppst.com.

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