1. Global Winds and Local Winds
Chapter 15.3

2. A. Global Winds and Local Winds
1.What causes wind?
2. Wind is caused by the movement of air which is caused by differences in air pressure.
Differences in air pressure are caused by the uneven heating and cooling of the Earth.
3. Warm air is less dense and creates an area of low pressure
4. Cold air is more dense and creates an area of high pressure.

3. Patterns of air circulation
GLOBAL WINDS
Patterns of air circulation
90*
Polar Easterlies
60*
Westerlies
30*
Trade WInds 0*
30*
60*
90*

4. Questions
What winds would Columbus have used to travel from Spain to the Caribbean?
Which winds would he have needed to return to Europe?
Would winds have favored European explorers seeking to travel east around the tip of Africa?

5. Trade winds
Eur. US

6. Prevailing Westerlies

7. No

8. B. POLAR EASTERLIES GLOBAL WIND
1. Extend from the North and South Poles from 90 to 60 degrees latitude.
2. Polar easterlies carry cold arctic air

9. C. WESTERLIES- GLOBAL WIND
1. These wind belts lie between 30 and 60 degrees latitude.
2. Westerlies flow toward the poles from west to east.
3. Affects the weather in the United States.

10. D. TRADE WINDS
1. Winds that blow from 30 degrees latitude almost to the equator at 0 degrees latitude.
2. Winds are named for the fact that these winds moved sailors across the Atlantic Ocean from Europe to the Americas.
3. Northeast Trade Winds blow from 30 degrees North toward the equator, 0 degrees.
4. Southeast Trade Winds blow from 30 degrees South toward the equator, 0 degrees.

11. E. DOLDRUMS- GLOBAL WIND
1. The trade winds meet at an area called the doldrums.
2. This area is located around the equator, 0 degrees latitude.
3. This is an area of low pressure where there is very little wind.

12. F. HORSE LATITUDES-GLOBAL WIND
1. Located at 30 degrees north and 30 degrees south latitude.
2. An area of little wind.
Name given by sailors who got stuck here because of lack of wind, travel time was slow.
Horses were thrown overboard to save water for sailors.

13. G. THE CORIOLIS EFFECT
1. The curving of winds due to the Earth’s rotation is called the Coriolis Effect.
2. Because of the Coriolis Effect winds curve to the east and west.
Winds traveling north curve to the right, or east.
Winds traveling south curve to the left or west.

14. H. Upwelling
Winds blowing along the coast push the coastal surface water.
When combined with the Coriolis effect, this motion moves surface water away from the coast.
As surface water moves outward, cold, plankton-rich water from the ocean bottom moves toward the coast and rises to replace the surface water.

15. I. THE JET STREAM
1. The jet streams are narrow belts of high-speed winds that blow in the upper atmosphere.
2. Unlike global winds, jet streams do not follow regular paths.
3. Knowing the path of the jet stream can help airplane pilots travel faster as they ride the jet stream.
4. Meteorologists can track a storm if they know the location of the jet stream.

16. J. Local Winds 1. Move short distances and blow from any direction.
Geographic features, a shoreline or a mountain can produce temperature differences.
2. Sea breeze
3. Land breeze
4. Mountain Breeze
5. Valley Breeze

17. K. SEA BREEZE- LOCAL WIND
During the day air over ocean is cooler and forms high pressure.
Warm air over land, low pressure.
Cool air moves inland and overtakes area of warm air.
Cool air has higher pressure than warm air.
1. Wind moves from sea toward land.

19. L. LAND BREEZE- LOCAL WIND
At night air over ocean is warmer, warm air rises and creates low pressure.
Air over land is cooler and creates high pressure.
Cool air moves toward ocean causing a land breeze.
1. Wind moves from land toward sea.

21. Sea Breeze and Land Breeze Animation

22. M. MOUNTAIN BREEZE LOCAL WIND
At night mountains cool faster than valley.
Cool air moves downward and creates a mountain breeze.
1. Mountain breeze moves down.
2. Cold air sinks.
3. Cold air / High pressure

23. N. VALLEY BREEZE LOCAL WIND
Sun warms the valley and the air above it.
Warm air rises and moves up mountain causing a valley breeze.
1. Valley breeze moves up.
2. Warm air rises.
3. Warm air /low pressure

25. O. High Pressure and Low Pressure
1. Low Pressure / Warm Air
2. Cloudy weather occurs with low pressure.
3. High Pressure / Cold Air
4. Clear weather occurs with high pressure

27. Animations-Coriolis Effect, Jet Stream

28. Quiz
Which type of breeze occurs when cool air moves from water toward land?
Which type of breeze occurs when cool air moves from land toward water?
What is the area of low pressure around the equator called? There is low pressure and little wind here.
High speed winds that occur in the upper troposphere and lower stratosphere?
Winds in the North curve to the right, or east, and winds in the south curve to the left, or west. This is known as….
What is upwelling?
Which wind belt affects most of the United States? They blow from 30* to 60* north and south.
Cloudy weather occurs with……………pressure.
Clear weather occurs with………………pressure.
These winds blow from any direction and move short distances.
Cold winds that blow from the poles to 60* latitude are called…..
These winds are located at 30* N and 30* south latitude.
These winds blow from 30* North and 30* South toward the equator.
This local wind is caused by cool air moving down the side of a mountain
This local wind is caused by warm air moving up from a valley.

29. Answers Sea breeze Land breeze Doldrums Jet stream Coriolis effect
Westerlies
Low pressure
High pressure
Local winds
Polar easterlies
Horse latitudes
Trade winds
Mountain breeze
Valley breeze