Visualization

I was going to draw a picture. I don't know how to do that very well on the computer.

So, how about you take a piece of paper out of your printer, rummage through your junk drawer, find a pencil and a ruler.

On the bottom of the paper draw two dots 3.9 inches apart, centered would be nice.

At the top draw two dots 2.4 inches apart, centered if you can.

Near the bottom third of the paper draw two dots about 2.2 inches apart, these should be centered, Then draw lines on the right side to connect the dots. Now the left side to connect the dots.

You have now connected the dots on upwelling flux.

You may begin to understand the equation,... now.