1. 19.2 Pressure Center & Wind

2. What is a cyclone? It is a center of low pressure.
The pressure decreases from the outer isobars towards the center.

4. What is an anticyclone? It is a center of high pressure.
The pressure increases from the outer isobars towards the center.

6. What is the rotation of cyclones & anticyclones in the Northern Hemisphere?
When the Coriolis effect are applied to LOW pressure centers:
and counter-clockwise around the low.
When the Coriolis effect are applied to HIGH pressure centers:
and clockwise around the high.

7. What is the rotation of cyclones & anticyclones in the Southern Hemisphere?
When the Coriolis effect are applied to LOW pressure centers:
and clockwise around the low.
When the Coriolis effect are applied to HIGH pressure centers:
and counter-clockwise around the high.

8. How does friction affect the flow of cyclones & anticyclones?
In either hemisphere, friction causes
Air to flow INWARD around a CYCLONE (LOW).
Air to flow OUTWARD around an ANTICYCLONE (HIGH).

11. What kind of weather can be expected from centers of low pressure (cyclones)?
Surface convergence (inflow of air) around a cyclone causes an upward movement of air.
Rising air is associated with cloud formation and precipitation.
Low-pressure centers can produce bad weather in any season.

12. What kind of weather can be expected from centers of high pressure (anticyclones)?
Surface divergence (outflow of air) around an anticyclone causes a sinking of air.
Sinking air produces clear skies, no clouds!

15. Global Temperature Patterns
YouTube:
Earth Wind
Current
The sun’s rays are weaker away from the equator causing less warming. The air here is cool.
The sun’s rays are stronger near the equator causing more warming. The air here is warm.

16. Air moves between the equator and the poles.
Global Winds
Hadley Cells.
Air moves between the equator and the poles.
Global Winds

17. What is the Rotating Earth Model of global winds?
It creates a convection system of six cells.

18. Global Winds Remember, winds are named from where they come!!! 60°N
Polar Easterlies - From 90°N to 60°N - Deflected to right
60°N
Prevailing Westerlies - From 30°N to 60°N - Deflected to right
30°N
Easterly Trade Winds - From 30°N to O° - Deflected to right
Doldrums 0°
Easterly Trade Winds - From 30°S to 0° - Deflected to left
30°S
Prevailing Westerlies - From 30°S to 60°S - Deflected to left
60°S
Polar Easterlies - From 90°S to 60°S - Deflected to left

19. What is a Polar Front?
A polar front is a stormy boundary where cold air from the Polar easterlies crashes with the warmer air from the Westerlies

20. Rotating Earth Model

21. How do continents influence winds?
In the Northern Hemisphere, where land masses break up the ocean surface:
Land masses disrupt wind patterns creating Monsoons.

22. What is a monsoon?
Monsoons are the seasonal reversal of wind direction associated with large continents, especially Asia.
In winter, the wind blows from land to sea.
In summer, the wind blows from sea to land.
India experiences a flow of warm water-laden air from the Indian Ocean.
YouTube:
Wind Patterns
YouTube:
Monsoon
Simulation

24. What are Local Winds? The local winds are caused either by
variations in temperature above land and water (sea & land breezes)
topographic effects (valley & mountain breezes)

25. Sea Breeze Occurs during the day Air moves from the sea
During the day, the land heats up & air above it becomes less dense, rises & forms low pressure.
During the day, air over the sea is cool. The cool air is more dense, sinks, & forms high pressure.

26. Land Breeze Occurs during the night Air moves from the land
YouTube:
Land & Sea
Breeze Explained
Occurs during the night
Air moves from the land
During the night, the land cools quickly & the dense air above sinks creating high pressure.
During the night, the sea stays warm & the less dense warm air above it, rises creating low pressure.

27. Valley Breeze Occurs during the day
Air moves from the valley UP the slope
During the day, the air heats up along the slopes more intensely than the air over the valley floor. This less dense warmer air glides up the slope.

28. Mountain Breeze Occurs during the night
Air moves from the mountain DOWN the slope
During the night, the air cools along the slopes more quickly than the air over the valley floor. This more dense cooler air glides down the slope.

29. What are Prevailing Winds?
Wind that blows more often from one direction than from any other.
In the United States, the Westerlies consistently move weather from west to east across the continent.