Eric Sloane’s Weather Book chapter 3
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. But 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.
Hi Mrs. Daly! I was wondering, for our semester project can I illustrate Corey’s Bow? (by the way, I LOVED the story!) And if I can, what do you want the pictures to be of?
Thanks!
-Isabel
Isabel,I would love for you to illustrate. What would you like to draw? There are people, bows and arrows, plants, and the diagrams which would look a lot nicer if they were drawn by hand, not done with computer graphics junk. The globe images with the basic continent outlines would be nice, or even a quarter globe or a half globe… Anything but the bare circle. And GGC-1835 from a distance with the garden or just the pine tree or corey holding his cone. Or the Baguettes… What is in your own imagination when you say you would like to illustrate? Mary