1. Global & Local Winds
Chapter 15, section 3:

2. Earth’s Atmosphere Quiz
When you’re finished with your quiz:
Keep your quiz on your desk & cover it.
Sit quietly at your desk. Read, work on your Heating Earth’s Atmosphere Lab packet (you should hand this in TODAY).
Earth’s Atmosphere Quiz

3. Name 3 pieces of info. you can figure out from this weather map.

4. Air exerts Pressure
Air Pressure: the force of air molecules pushing on an area.
The greater the force, the higher the pressure.
How is air pressure related to wind?
Air molecules are always moving. Each time a molecule bounces off an object, it pushes, or exerts a force upon that object.
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Air molecules are always moving.

5. Air Pressure is Related to Altitude and Density
Air pressure decreases as you move higher in the atmosphere (less air above you)
Density of air decreases as you move higher in the atmosphere.
Air pressure at any area on Earth depends on the weight of the air above that area.
Air Pressure is Related to Altitude and Density
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6. Pressure & Air Motion
Differences in pressure causes movement of air.
High Air Pressure
Low Air Pressure
Low Air Pressure
Movement of Air
Air pressure can vary at any two locations at the same altitude.
Wind: the movement of air caused by differences in air pressure.
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7. Uneven Heating Causes Wind to Move
Large pressure difference - strong wind
Small pressure difference- slight wind
Wind
Wind: Air in motion.
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8. Uneven Heating of Earth:
N/S poles: spread out sunlight, less of sun’s energy, cool & dense air, high pressure
Equator: direct/strong sunlight, high temp. (warm air rises), low pressure
Where on Earth would you expect > heating? Less heating?
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9. High and Low Pressure Areas
High pressure- air sinks
Usually results in several days of clear sunny skies
Air rises in low pressure areas and forms water droplets
Usually results in rain and storms
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10. Global Winds: long distance patterns of air circulation caused by convection cells & Coriolis effect
Local Winds: caused by geography of an area
2 Main Types of Wind:

11. Earth’s Rotation Affects Wind Direction
Coriolis Effect: The influence of Earth’s rotation on winds & objects moving on Earth.
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12. Global Winds
Global winds: Travel thousands of kilometers in steady patterns. Global winds are caused by uneven heating between equator & N/S poles.
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13. Calm Regions & Global Wind Belts
Doldrums “dull/sluggish”:
Low pressure equator
Warm air rises & spreads toward poles
Rising moist air -->clouds & heavy rain
(2) Horse Latitudes: (windless)
High pressure 30˚ N/S
Warm air from equator cools & sinks
Clear & dry weather
Air usually stays calm in high/low pressure zones. Winds are light & often change direction.
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14. Global Winds: Trade Winds: Blow East from Horse latitudes to Equator
Strong & steady. Die out as they reach equator
Westerlies: (blow from the West)
Blow from Horse latitudes to poles
Bring storms across U.S.
Dense air (in horse latitudes & other high pressure zones) moves toward low pressure zones (like the doldrums)
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15. Polar Easterlies: (blow from East)
Blow from polar regions to mid-latitudes
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16. Science Starter: Calm Areas and Wind Belts
Name
Characteristics
(1)
A low-pressure zone near the equator.
(2)
High-pressure zone at about 30° N and 30° S of the equator.
(3)
Winds that blow from the East from the horse latitudes to the equator.
(4)
Winds that blow from the West from the horse latitudes to the poles.
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17. Jet Streams Flow Near the Top of the Troposphere
Not all long distance winds Earth’s surface.
Jet Streams: Flow in a wavy pattern, move from W -->E, can pull cold air down into US, pull warm air up into Canada, flow faster than surface winds
Each hemisphere has 2 jet streams: (1) Polar jet stream (2) Subtropical jet stream
Jet Stream: Long distance wind that flows in the upper Troposphere.
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18. Local winds-sea/land breezes
Local winds: change daily, flow within a small area, typically flow in a regular pattern
How would this local wind pattern change at night?
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20. Local Winds-mountain/valley breezes
During Day
Local Winds-mountain/valley breezes

21. Local Winds-mountain/valley breezes
During Night
Local Winds-mountain/valley breezes

22. Measuring Air Pressure
Barometer: an instrument that measures air pressure.
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23. Science Starter:
How does the uneven heating of Earth’s surface cause winds to flow?
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24. Two barometers are placed one kilometer apart
Two barometers are placed one kilometer apart. One shows higher pressure than the other. What will happen to the air between them?
Science Starter:
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