1. 19.3: Global Wind Patterns

2. Factors that Affect Winds
Temperature difference between equatorial regions and the poles
Rotation of the Earth
wattsupwiththat.com

3. Factors that Affect Winds
Locations of the Continents
Time of year
Local topography (mountains, valleys, plains, etc.)
wallpaperstock.net
science-class.net

4. Winds on a Non-rotating Earth
Warm air near the equator would rise and move toward the poles aloft
Cold air near the poles would move toward the equator at the surface

5. Winds on a Non-rotating Earth

6. Effects of Earth’s Rotation
Coriolis effect prevents air from flowing straight to equator from poles
Also, air from the equator cools & sinks long before reaching the poles

7. Three-Celled Circulation Model
3-Celled Circulation Animation

8. Three-Celled Model Weaknesses
Mid-latitude (between 30° & 60° latitude) winds are oversimplified
Effects of continents or seasons not accounted for
Upper-level winds are more complicated than the model shows

9. Three-Celled Model Strengths
Latitudes other than between 30° & 60° are fairly accurate
Model is an average; good for climate studies (long-term pattern)

10. Wind and Pressure Belts
Intertropical Convergence Zone (ITCZ): low pressure zone created by maximum heating at the equator
principiojoanne2196.blogspot.com

11. Wind and Pressure Belts
The ITCZ is hot & humid with little or no wind; rain is frequent (doldrums)
tnhsprgteam.blogspot.com

12. Wind and Pressure Belts
ITCZ encircles the Earth; migrates north and south depending on the season
en.wikipedia.org

13. The ITCZ: Can U find it?

14. Three-Celled Circulation Model