A meteorologist uses computer graphics to enhance our understanding of high and low pressure systems.
In the still-shot above, find the area labeled ‘H’ for high pressure (to the left of the weatherman); above this is a convergence of air flows. When the upper air is cool its molecules move closer together; they converge.
When air is warm, molecules move away from each other; this is called rarefaction. Acting like a vacuum, the evacuated spaces of rarefied air Pull cooler air into it to fill the gaps.
Note that the vertical arrow points downward in a high pressure system; the air descends from above, spattering outwardly (clockwise and centrifugally, shown by the purple arrows) as it compresses against the ground level air.
Now find the area labeled ‘L’ for low pressure (to the right of the weatherman); above it is a divergence of air flows. In a low pressure system, the warmer ground level air is Pulled upward (the vertical arrow points upward), funneled into a vortex, which, in severe low pressure systems, could become a devastating tornado. Purple arrows are spinning counter-clockwise and centripetally.
The wind tends to blow from a cool area to a warm area, even laterally, as it does from sea to land. Warm air is more rarefied, meaning there is more space between its molecules. Warm air is lighter, so it rises, leaving a low pressure area below. Cold air is more dense, meaning there is less space between its molecules. Cool air is heavier, so it sinks into lower spaces, creating a higher pressure at ground level.
Wind Follows the Right-Hand Rule of Physics
To participate in a guided activity, please pretend that the surface of your computer display is horizontal instead of vertical. Imagine the graphic below to be flat on a surface that you are viewing from above.
To mirror a low pressure system, rest your right hand on the graphic above, centered on the ‘L’ (low pressure system). Make a fist and lift your thumb, which should be pointing upward (or toward yourself and away from the screen).
Notice that your fingers are coiling counter-clockwise, in alignment with the arrows of the low pressure system graphic, upon which your fist rests. Ground-level wind follows the “right-hand rule” of physics, which states that if one aligns his/her right thumb in the direction of a flowing electrical current, then corresponding magnetic field lines will follow the direction of his/her curled fingers. (Illustrated below.)
To mirror a high pressure system we reverse the procedure. Point your right thumb downward (toward the computer screen), so that it touches the ‘H’ on the left side of the graphic.
This feels a little awkward, but you should be able to tell that your fingers are now coiling in a clockwise direction, aligned with the high pressure system graphic. In a high pressure system the cool air above descends (thumb down) to ground level.
Wind Blows from High Pressure to Low Pressure
Movement of air not only moves vertically, but it also moves from high pressure to low pressure laterally at ground level. These systems, as shown below, are in a relationship, evidenced by the arrows connecting the high pressure system on the left to the low pressure system on the right. With your growing knowledge of Quadernity, you are surely by now suspecting a four-quadrant circuitry. Oh, please, say it is so!
Four Quadrant Circuitry
The arrows depicting the upper air flows reflect convergence and divergence. These horizontal arrows are pointing to the right; however, to make a full circuitry they should be pointing to the left (see the graphic below the photo). The producer of the weatherman’s graphics is uninformed about Quadernity, so he/she did not think that far.
Using the lens of Quadernity, we recognize that, in the upper air-stream, the air in the low pressure system on the right, which is diverging in a counter-clockwise direction, has to flow back into the high pressure system, which is converging in a clockwise direction.
Let us follow the feedback loop full circle. Beginning in the upper left corner of the graphic below, trace the arrows around the circuit. This graphic corrects the still shot of the meteorologist several paragraphs above. The lower two quadrants represent the ground level wind, which moves from high to low pressure regardless of the relative temperatures. This was also shown in the section just above this one, where the two systems were related by arrows connecting them, high to low.
Even though convergent and pressurized air are both showing Spin, there is a difference between them. When molecules in air pull themselves together, we call it convergence. When molecules in air are pushed together by an outside force, we call it pressurization; in the example given, the force that pressurizes the air is the ground itself, which provides resistence.
Molecules that are close together (regardless of how they got that way) tend to move to wherever they can meander about with ample freedom, so we would see the cold, pressurized air moving toward a low pressure area.
Consider our Spin and Span labels as you follow the arrows in the graphic reprinted below, which is now overlaid with cones that emphasize convergent Spin and expansive Span.
Start at upper left and follow arrows in the circuit:
- Cool air converges (spin is clockwise, thumb down)
- Span as cool air meets resistance at ground level and spreads out (still clockwise)
- Warm air rises, leaving low pressure at ground level (spin is counter-clockwise, thumb up)
- Span as warm air diverges (still counter-clockwise)
Our new terms, Spin and Span, allow us to organize our insights in a way we may not have thought of before.
- Both Female and Male Spin and Span.
- High pressure (downward Span at ground level is Female, LRQ) and divergent warm air (upward Span is Male, URQ) are special instances of Span. Both of the Right Quadrants are Objects that have Span, or Push.
- Low pressure (LLQ, Male) and convergent cool air (ULQ, Female) are special instances of Spin. Left Quadrants are Subjects that Spin, or Pull.
- Both clockwise movements (1 & 2 from numbered list above) are Female (ULQ & LRQ in the Chalkboard Quadrants). Both counter-clockwise movements (3 & 4) are Male (LLQ and URQ).
- The left side cone is Female and the right side inverted cone is Male. Spin of Female Subject delivers Objects that Span to Lower Quadrants, and Spin of Male Subject delivers Objects that Span to Upper Quadrants.
- Although the orientation of the cones or the High and Low Pressure systems is not in a figure 8 as we have grown accustomed, this does not negate the feedback between the two. Orientation is arbitrary; we must learn to see the dynamical feedback of Quadernity in any orientation.
Can you identify the same sequence in the illustration below (reprinted from this article) of how massive fires reproduce the weather necessary to fuel the fires?
Quadernity has made a case for the four-quadrant circuitry, but to assure you that I am not forcing the issue, let’s think it through just a bit more. When the warm air rises and rarefies, it eventually cools enough to stop diverging. In other words, divergence is self-limiting. The convergence of cool air increases pressure against the ground, which heats the air, slowing the convergence and initiating divergence. Convergence is, therefore, also self-limiting.
If the two vertical systems of our example were independent of each other, the high pressure system would Span out at ground level and lose its energy potential, and the low pressure system would Span out through the divergent upper air stream and lose its energy potential. In both cases, the systems would be exhausted after only a momentary blip on the weather-screen.
However, we know that some weather systems last for days. How so? Well, consider what happens when high and low pressure systems are conjoined. Instead of the warmed divergent air simply Spanning away from the low pressure system, never again to be useful to it, the warmed air cools as it Spans outward and is Spun into a low pressure system nearby where the cool air descends. As this descending air meets the ground resistance, it Spans outward to enter the upward Spin of the low pressure system again.
The low pressure system is reset by input at ground level, and the high pressure system is reset by input in the upper air stream. Through feedback, each system recovers its energy potential from the other. The two systems are united. Together they co-operate to improve sustainability.
We can all take a note. Cooperation can make us all winners.