Ahh, thats excellent.
I'm a FreeBSD man myself, but I'm sure that without too much tinkering you can get my code working on your system.
Do you have gd installed? If not, grab it and install it and give me a whistle. My code uses gd to actually create the image.
Basically all I do is take raw wind samples (in my case, every 5 seconds), take the direction to calculate the start and end of the arc, and the speed to make the radius.
Perhaps the hardest part is the time calculations, I scale over 1, 4 or 24 hours so the colour scale smoothly transitions over the period. Depending on where the current sample is in the time domain determines what colour I draw the arc.
Draw the scales, plonk some labels, write the output, done.
Are you comfortable coding in C? Can send you source. Possible I could link it static and send you executable? Not sure on that one!
R.