Posts Tagged ‘wind’

Beaufort Verse

Admiral Francis Beaufort spent enough time with both his own diary and his ships logs to recognize the importance of making naval reports more uniform and useful. Everyone really has a different idea of what sort of breeze is “gentle” or “strong”, so he thought it would be useful to choose terms that would be more universal by their relationship with specific observations — and after about 32 years, the Royal Navy agreed. This is the origin of the Beaufort Wind Scale, which has been adapted for land use by adding observations that apply to trees and houses — not just waves!

Of course modern weathermen — on land or at sea — use wind speeds in knots, miles, or kilometers per hour, but it sometimes happens that these more objective and specific measures — so important in official reports — have the effect of making us less observant. Somebody asks for the wind speed, and we run for the newspaper or the phone instead of looking out the window. In this way, we detach ourselves from experience. Notice the weather!

In your weather observations, use drawings as well as words, and describe the evidence of the wind, not just the numeric speed. You will see more that way. Here’s a very simple chart to use.

30 chart alone

Meantime, unable to resist the opportunity to make something more accessible through verse, I have put Beaufort’s work to rhyme.

Beaufort Wind Scale

Beaufort naught leaves ponds like glass

Reflected swans for real may pass.

Zero wind leaves water like a mirror; and smoke rises straight up.

Drifting smoke is Beaufort 1

Water scales; but waves are none.

A slight wind causes water to have the appearance of fish scales; smoke drifts a little.

I turn my face to Beaufort 2

While glassy waves touch my canoe.

A little more wind actually makes waves and can be felt on the face.

A gentle breeze is Beaufort 3

Rustling leaves and just-breaking sea.

As wind speed approaches 10 mph, the waves become strong enough to break, and on land, the leaves rustle without ceasing.

Branchlets move for Beaufort 4

And milk-white horses trot ashore.

The next sign of strengthening wind is a little white on the cresting waves; still not threatening, but getting brisk. Small branches move in this wind.

Beaufort 5, a fresh’ning breeze,

Lengthens waves and bends young trees.

Somewhere near 20 mph, the wind begins to bend young trees. Waves become longer, and the “white horses” become numerous and insistent.

Whistling wires are Beaufort 6

Men with umbrellas are in a fix!

If you use an umbrella, you know that sometimes the wind is just too strong. At sea, this is when the spray begins to come up.

With heaping seas and blowing foam

‘Gainst Beaufort 7, ’tis hard to roam.

Eventually, even the human body is so buffeted as to make it hard to walk in the wind. This is about 30 mph.

Snapping twigs — spindrift at sea

Beaufort 8 is the gale for me!

We really have a storm now — a gale. Small parts of trees and plants begin to break in the wind, and the foam is blown above the water. This gets us up to 40 mph. “Gale” has a specific meaning for Beaufort; not just big storm, but these specific observations.

Beaufort 9 is a howling gale

Testing the ship and the roofing nail.

Nobody likes to lose shingles, but it happens; and you better have a solid ship if you are at sea.

Trees by the root and ships in a wave

Beaufort 10 is a terrible knave.

Basically, this is just below hurricane force.

If you’re on board for B-11

Best prepare to knock at heaven.

Hurricane. Anyone can be hurt; any building is up for grabs.

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Assignments #3

Dear weather students,
Your primary homework is to read chapter three of your respective books; reflections below. Please don’t leave it for Thursday night; there are too many concepts to absorb in one evening.
Second, you must each choose a weather project. It can be a book report (an enthusiastic and interesting one), a biography, the construction of a weather observation tool, or anything else that I may have mentioned from time to time. It must be illustrated; your work with Ana is so beautiful. Describe your intended project and whether you want to report soon or at a later date. If you wish to illustrate a weather story as your project, that would be great; you can make one up, choose one from any of the weather books, or illustrate Corey’s Bow. If you choose my story, let me know and I get you a printed copy. I am sure Ana would be delighted to help you.
Third, let’s begin to record cloud and wind observations. Watch the direction and strength of the wind. A very simple chart has been sent for your use. Describe, name if you can, and draw as best you can, the clouds of the day. Notice the direction and strength of the wind. For strength, notice the trees — what is the width of thickest branch that is moving; notice any flags — how well are they lifting and are they flapping; notice the grass — how long is it and is the wind rippling across the field or just bending a little; notice what moves — are papers lifted and blown, is sand or dirt blowing (no snow yet!)
You can re-make the chart so that you have more room for your drawings and observations, or you can attach them on the back.

Eric Sloane’s Weather Book chapter 3

Sloane has a very clear and helpful discussion of air pressure, the barometer, and the effects of changing air pressure on the ear. If you are in the older class and having trouble with these concepts, find a younger sibling and read Sloane.
You might make Sloane’s very simple barometer for your weather project. It’s so very simple that it won’t necessarily work for a long period of time, but it should work long enough to be interesting and informative. Here’s another example of the same idea, from an astronomy website. It has more parts and might be more useful.
For an extra challenge, look closely at his chart on page 25 and try to figure out why the barometric and wind readings mean what he suggests. Yesterday’s post (opposing winds) about the interaction between prevailing winds and storm winds will help you.
Sloane does not use the word Coriolis, but if you have read Corey’s Bow, can you see what he is talking about with wind direction near a low-pressure area?

Jack Williams Weather Book chapter 3

p. 31-34 Air pressure

Williams begins this chapter on wind by discussing air pressure. One thing I found interesting was his comparison of air pressure at the top of the Sears Tower in Chicago with air pressure in a storm. It would be quite a storm that would give as low a pressure over the sea as any resident of the Sears Tower (such as Patrick B-H) experiences every day. Of course the bottom of the Sears Tower is not sea level either, right, so these men and women don’t experience such a change in pressure as would accompany a storm.┬áBut it shows you that you need more than a barometric pressure number to get weather information. You need to know how it’s changing not just what it is.

p. 35 Pressure Gradient Force — PGF

This is just an abbreviation for the simple fact that low pressure is a kind of valley and high pressure flows into low pressure. This is the basic source of wind. Before, he was saying that basic source was the sun, but of course the sun heats things, and that raises their pressure if they are confined. Air is not confined except by its own weight, so it moves when heated: that’s the wind!

p. 36-37 Coriolis Effect

If you have read up to chapter 10 of Corey’s Bow, I hope you will smile when you come to his explanation of the Coriolis effect. As most people do, he presents the effect from the poles towards the equator, which is easy, but he does not talk about going the other way. You know that, in fact, the direction of the Coriolis effect is the same from equator to pole, but it was not obvious, was it? When I asked what would happen from equator to pole, the spontaneous guess was that the wind would go the other way, left. The wind coming from the north pole does not have any motion from the earth’s turning, and this fact does not seem to need your notice. The air (wind) goes south; its destination is moving east on it; it lands west — to the right of its destination.

But from the equator, air and everything else is already going 1000 mph east, and this momentum carries it eastwards faster than the eastwards movement of its destination. So it lands east — again to the right of its destination.

p. 38-40 Jet stream

Williams has an interesting discussion of the jet stream. Notice the high speed in the center. Had you any thought of the wind being that fast? 190 mph is a speed we never really experience. Planes go that fast, but we are quietly enclosed.

p. 41-43 World winds

Here is his discussion of the trade winds, which I hope you will recognize as the Hadley cell and of the Polar winds, which are the Polar cell. In addition, he has some specific areas of the world where there are high and low pressure areas that persist for other reasons. Look at them and ask yourself why the pressure is high or low in that area.

p. 44 Mountain winds

Look at the way that air flow is diverted as it flows over a mountain. Where is the turbulence? Slowly pour some cream or milk into some coffee and watch the swirls of turbulence in the area where the cream slides alongside the coffee.

p. 45 Beaufort Wind Scale

Take a few minutes to notice the kinds of observations that can give you a wind speed — on land or on the sea. If you watch, you can figure out the wind speed for yourself. This is the kind of observation I would like you to make on your chart.

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