19.3: Global Wind Patterns

http://www.toonpool.com/user/589/files/wind_farm_desert_island_128775.jpg

Factors that Affect Winds• Temperature difference between

equatorial regions and the poles• Rotation of the Earth www.physicalgeography.net

wattsupwiththat.com

Factors that Affect Winds• Locations of the Continents• Time of year• Local topography (mountains,

valleys, plains, etc.)

science-class.netwallpaperstock.net

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

Winds on a Non-rotating Earth

http://universe-review.ca/I09-15-circulation1.jpg

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

Three-Celled Circulation Model

3-Celled Circulation Animation

Three-Celled Model Weaknesses

1. Mid-latitude (between 30° & 60° latitude) winds are oversimplified

2. Effects of continents or seasons not accounted for

3. Upper-level winds are more complicated than the model shows

Three-Celled Model Strengths

1. Latitudes other than between 30° & 60° are fairly accurate

2. Model is an average; good for climate studies (long-term pattern)

Wind and Pressure Belts• Intertropical Convergence Zone

(ITCZ): low pressure zone created by maximum heating at the equator

principiojoanne2196.blogspot.com

Wind and Pressure Belts• The ITCZ is hot & humid with little

or no wind; rain is frequent (doldrums)

tnhsprgteam.blogspot.com

Wind and Pressure Belts• ITCZ encircles the Earth; migrates

north and south depending on the season

en.wikipedia.org

The ITCZ: Can U find it?

http://cawcr.gov.au/bmrc/clfor/cfstaff/jmb/03May15a.html

Three-Celled Circulation Model

www.newmediastudio.org