#356 Postby Air Force Met » Wed Apr 12, 2006 3:55 pm
I seem to remeber that at the SURFACE...high pressure related winds are weaker than low pressure related winds (again, if I recall correctly, this is a function of the PGF and Coriolis/Centrifugfal forces working differently in a high vs a low). This dyanmic doesn't change aloft, does it?
No it doesn't change. Remember, high pressure winds aren't weaker than low pressure winds, either. Winds are a function of their pressure gradient force only, regardless of whether they are in a high or low. It's just that you are much more likley to have a step PGF in a low than in a high...UNLESS you have a low next to a high increasing the PGF. Highs can't build to the extend that a low can depend before the PGF spreads out, which is why the wind field is weaker. Lows are creating a mini-vacuum, so air is leaving at a faster rate than it is filling, thus the pressure lowers as the PGF increases.
In a high, air is filling in faster than it can be moved out but it is a less violent process at the sfc and aloft than what is going on in a low, so the air has a chance to spread out...as does the PGF...and it occurs over a broader area...whereas the low deepens in a smaller area near the center. Thus...a broader wind field and weaker PGF in a high.
How do anticyclones aloft compare to surface anticyclones? Do they also have a broader windfield than their surface "cousins"?
They are the same. Again, it's a function of their PGF (and we call it CGF aloft...contour gradient force due to the fact we use contour maps instead of pressure maps).
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