Summary: Winds on Upper-Level Charts

<strong>Summary</strong>: <strong>Winds</strong> on Upper-Level Charts
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height contours
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<strong>Summary</strong>: <strong>Winds</strong> on Upper-Level Charts
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PGF
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PGF points from higher to
lower heights

<strong>Summary</strong>: <strong>Winds</strong> on Upper-Level Charts
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PGF
CF
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Coriolis points opposite the
PGF to balance (no friction
at upper levels)

<strong>Summary</strong>: <strong>Winds</strong> on Upper-Level Charts
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PGF
wind
CF
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To be consistent, the wind points
along the height contours!!

Which point has the bigger wind

Which point has the bigger wind
PGF
PGF
The size of the PGF depends on
the contour spacing

Which point has the bigger wind
PGF
PGF
CF
CF
A bigger PGF implies a bigger
Coriolis force to balance

Which point has the bigger wind
PGF
wind
PGF
wind
CF
CF
And a bigger Coriolis force
implies a bigger wind

Which point has the bigger wind
PGF
wind
PGF
wind
CF
CF
So tighter height contours mean bigger winds!!

This morning's (Fri) 300 mb chart, showing height contours, winds
(arrows with feathers) and wind speeds (colors)

<strong>Summary</strong>: <strong>Winds</strong> on Surface Maps
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PGF
wind
CF
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Basically the same deal at the ground, but......

<strong>Summary</strong>: <strong>Winds</strong> on Surface Maps
L
PGF
wind
CF
H
Basically the same deal at the ground, but......because of friction,
the winds cross the isobars towards lower pressure.

.....so maybe something like this
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schematic winds on a surface map,
converging towards low pressure

This morning's (Fri) surface map, showing isobars (contours) and
winds (arrows with feathers)

Schematic showing winds in balance at upper levels (roughly),
while......
.....at the ground, winds are affected by friction.

Surface Convergence and Rising Air
Now, at the ground, the air crosses the isobars toward lower
pressure. Which means.....
●
Around low pressure the air tends to converge into the center,
while.....
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Surface Convergence and Rising Air
Now, at the ground, the air crosses the isobars toward lower
pressure. Which means.....
●
Around low pressure the air tends to converge into the center,
while.....
●
Around high pressure the air tends to diverge away from the
center.

As air converges into a low center, it has to go somewhere.....so it
rises. And as air diverges away from a high, it's replaced by air
sinking from above. So the basic rule of thumb is
low pressure center: air is rising
high pressure center: air is sinking

As air converges into a low center, it has to go somewhere.....so it
rises. And as air diverges away from a high, it's replaced by air
sinking from above. So the basic rule of thumb is
low pressure center: air is rising
high pressure center: air is sinking
And keep in mind that rising air tends to produce clouds and
precipitation, which brings us back to our original rule of
thumb:
Relatively speaking, cyclones are areas with cloudy and
rainy weather, while anticyclones are typically clear and
sunny!

Forecast for today (Fri) at noon, showing pressure (thin white
contours) and predicted rain (green) and snow (blue and pink)