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1

in the green shaded area the 

wind streamlines are generally splitting apart from trough axis to ridge axis. This is called diffluence

2

Note that in the green shaded area the wind streamlines are generally splitting apart from trough axis to ridge axis. This is called diffluence and it is very characteristic of trough/ridge systems in the jet stream that

diffluence occurs east of troughs and confluence east of ridges

3

Note that in the green shaded area the wind streamlines are generally splitting apart from trough axis to ridge axis. This is called diffluence and it is very characteristic of trough/ridge systems in the jet stream that diffluence occurs east of troughs and confluence east of ridges.
That would suggest to

the eye, at least, that divergence is occurring in the green region.

4

That would suggest to the eye, at least, that divergence is occurring in the green region. But this is the 500 mb level, the level at which

 Non‐divergence should be occurring

5

Note that along each streamline, however, the 

wind speeds are stronger near the trough axis and weaker near the ridge axis.

6

Note that along each streamline, however, the wind speeds are stronger near the trough axis and weaker near the ridge axis. The inset shows the

streamline that stretches from A to B on the chart. 

7

Note that along each streamline, however, the wind speeds are stronger near the trough axis and weaker near the ridge axis. The inset shows the streamline that stretches from A to B on the chart. You will note that speed convergence is occurring 

 along the streamline (meaning, that the air parcels on the west side of the streamline are "catching up" to the air parcels on the east side)

8

You will note that speed convergence is occurring along the streamline (meaning, that the air parcels on the west side of the streamline are "catching up" to the air parcels on the east side).
Thus in the concept equation above, diffluence would have a

 positive sign

9

Thus in the concept equation above, diffluence would have a positive sign, but there would be a 

negative speed divergence

10

Thus in the concept equation above, diffluence would have a positive sign, but there would be a negative speed divergence. At the Level of Non‐Divergence, these two terms are

 very nearly equal in opposite, producing non‐divergence.

11

The relative vorticity can be expressed in natural coordinates as:

12

in this form the relative vortiity has two components:

the shear vorticity

the curvature vorticity

13

show the shear vorticity

14

show curvature vorticity

15

absolute vorticity =

shear + curvature + coriolis parameter

16

Shear vorticity

This is the change in wind speed over distance

17

shear is positive when

If the shear produces a cyclonic (counterclockwise in Northern Hemisphere)
spin of air

18

Curvature vorticity:

It is determined by the turning ratio of the air over time.

19

curvature vorticity is positive when

The stronger the rate of directional turning, the higher the curvature vorticity value will be. If the turning is cyclonic, the value will be positive

20

Earth vorticity. it is calculated from the formula:

f= 2 Ω sin o|

21

The earth vorticity (or the coriolis parameter), increases when 

moving from the equator toward the pole.

22

The earth vorticity is always positive except at 

the equator, where it is zero

23

Absolute vorticity becomes positive or increasing under the following conditions:

  1. positive shear vorticity
  2. positive curvature vorticity
  3. increasingly positive earth vorticity

24

positive shear vorticity

Wind speed increasing when moving away from center point of trough

25

positive curvature vorticity

A counterclockwise curvature in the wind flow. This occurs in troughs and shortwaves

26

increasingly positive earth vorticity

A south to north movement of air. Coriolis parameter increases (becomes more positive) when moving from the equator toward the poles.

27

Vorticity maximums will be located in areas where 

the most vorticity terms are positive and largely positive in magnitude

28

show positive shear vorticity, positive curvature vorticity and positive earth vorticity

29

Absolute vorticity becomes negative or decreasing under the following conditions:

negative shear vorticity

negative curvature vorticity

decreasingly negative earth vorticity

30

negative shear vorticity

Wind speed decreasing when moving away from center point of trough.