1. Chapter 15 Section 3
Global and Local Winds

3. What is air pressure?

5. The air above you.
It is the weight of the atmosphere as it pushes down on the Earth’s surface is called air pressure.

6. Identify the areas that have warm & cold air.

7. Which area has the most dense air?
Cold Air
Warm Air

8. Which sides have high and low air pressures?
Cold Air
Warm Air
Dense Air
Less Dense Air

9. What is the rule for atmospheric pressure reaching equilibrium?
Cold Air
Warm Air
Dense Air
Less Dense Air
High Air Pressure
Low Air Pressure

10. Which way will the air molecules begin to move?
Cold Air
Warm Air
Dense Air
Less Dense Air
High Air Pressure
Low Air Pressure

11. When will the air movement stop?
Cold Air
Warm Air
Dense Air
Less Dense Air
High Air Pressure
Low Air Pressure

12. The atmosphere is now at equilibrium.

13. The movement of air is called ____?
wind
Cold Air
Warm Air
Dense Air
Less Dense Air
High Air Pressure
Low Air Pressure

14. Does air Move?
YES!!!!

15. Air Movement
Wind is the movement of air caused by temperature and air pressure differences
The greater the difference, the faster the wind moves

17. What causes changes in Air Pressure???
Differences in air pressure are caused by the uneven heating of Earth

18. How does the Earth heat unevenly?

19. A B C Which area receives direct sunlight
(A, B, or C)?
The poles always receive indirect sunlight (light hits at an angle). B
The equator always receives direct sunlight. C

22. Warm air rises upslope during the daytime.

23. Cool air sinks down-slope during the night-time.

24. Warm Air Cold Air Convection Current Convection Current Warm Air

25. What happens on Earth when there are differences in air pressure?

26. Uneven heating produces pressure belts which occur every 30° latitude
Air Pressure
Since the differences in air pressure are caused by the uneven heating of Earth
Uneven heating produces pressure belts which occur every 30° latitude

27. Pressure Belts
As warm air rises at the equator and moves toward the poles, it cools
As it cools, some of the air sinks around 30° north and south of the equator

29. Pressure Belts
At the poles, cold air sinks and moves towards the equator
Around 60° north and south, the air begins to heat up and rise

30. Global Winds
The combination of pressure belts and the Coriolis Effect cause global winds

31. Winds, and weather patterns curve due to Earth’s rotation.
Coriolis
Effect:
Winds, and weather patterns curve due to Earth’s rotation.

32. Coriolis Effect
• Rotation of the Earth causes moving air and water to change directions
• Northern Hemisphere winds curve to the right
• Southern Hemisphere winds curve to the left.

35. There are 2 types of winds…
1. Local Winds
2. Global Winds

36. Global Winds
The combination of pressure belts and the Coriolis Effect cause global winds
Do not travel North and South because of the Earth rotating on its axis.

37. Global Winds There are 4 Global Winds Polar Easterlies
Prevailing Westerlies
Trade Winds
Doldrums

38. Global Winds

39. What are the global wind systems?

40. Polar Easterlies Wind belts that extend from the poles to 60° latitude
Formed from cold sinking air moving from the poles creating cold temperatures
Slow winds influence weather

41. Prevailing Westerlies
Wind belts found between 30° and 60° latitude
Flow towards the poles from west to east carrying moist air over the United States (Impacts US weather)

43. Trade Winds Winds that blow from 30° almost to the equator
Called the trade winds because of their way to easily propel trading ships across the ocean
- In the Northern Hemisphere, the trade winds blow from the northeast and are known as the Northeast trade winds - In the Southern Hemisphere, the winds blow from the southeast and are called the Southeast Trade Winds.

45. Doldrums
Located along the equator where no winds blow because the warm rising air creates and area of low pressure

46. These are located at the equator, surface winds are calm and weak.
Why are they called doldrums?
Sailors found that there were no winds near the equator for a period of time. The ships were essentially stuck in one place, not being able to move forward. These calm periods were called doldrums.
Today, to be “stuck in the doldrums” means that you’d like to be doing something, but you’re stuck waiting for something to happen so you can begin moving forward.

47. Horse Latitudes
Occur at about 30° north and south of the equator where the winds are very weak
Most deserts on the Earth are located here because of the dry air

49. Jet Stream
The jet streams are narrow belts of high speed winds & high pressure that blow in the upper troposphere and lower stratosphere
Separates warm air from cold air
Moves East to West

53. Local Winds • Cover short distances • Blow from any direction • 2 Types of Local Winds – Sea Breezes- from sea to land – Land Breezes – from land to sea

54. Local Winds
Generally move short distances and can blow in any direction
Caused by geographic features that produce temperature differences

55. Sea Breezes
High pressure is created over the ocean during the day and low pressure over land due to uneven heating
Air moves from the ocean to the land creating a sea breeze

56. Land Breezes
Low pressure occurs over the ocean during the night and high pressure over land due to the uneven heating of earth
This causes wind to move from the land to the ocean creating a land breeze

59. HP LP DAYTIME WIND DIRECTION SEA BREEZE CONVECTION CURRENT

60. HP LP NIGHTTIME LAND BREEZE WIND DIRECTION CONVECTION CURRENT