Notes

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Outline

1	Chapter 8: Development of High- and low-Pressure Systems
2	Main Points to Learn Because extratropical cyclones are the parent storms for many hazardous weather, it is essential to understand how they are created and demised. Extratropical cyclones (i.e., low-pressure systems) develop as a direct result of acceleration created by the imbalance between the pressure gradient force and the Coriolis force. Frictional force in the boundary layer ultimately destroys extratropical cyclones. High-pressure systems also evolve in response to force imbalance, although cooling and heating play more important roles.
3	Geostrophic Balance
4	Centrifugal Force
5	Gradient Wind Balance The three-way balance of horizontal pressure gradient, Coriolis force, and the centrifugal force is call the gradient wind balance. The gradient wind is an excellent approximation to the actual wind observed above the Earth’s surface, especially at the middle latitudes.
6	Super- and Sub-Geostrophic Wind
7	Upper Tropospheric Flow Pattern
8	Convergence and Divergence
9	Convergence/Divergence and Vertical Motion
10	Example: A 300mb Weather Map
11	Convergence/Divergence in Jetstreak
12	Combined Curvature and Jetstreak Effects
13	Frictional Effect on Surface Flow
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15	Surface Heating and Cooling
16	Developments of Low- and High-Pressure Centers
17	Vertical View of High/Low Developments
18	Rotating Annulus Experiment
19	Carl Gustav Rossby (1898-1957) Carl Rossby mathematically expressed relationships between mid-latitude cyclones and the upper air during WWII. Mid-latitude cyclones are a large-scale waves (now called Rossby waves) that grow from the “baroclinic” instabiloity associated with the north-south temperature differences in middle latitudes.