Global Atmospheric Circulation & Prevailing Winds: Key Concepts and Patterns

Hadley Cell

Convection cell located between 0°-30° latitude.

Ferrel Cell

Convection cell located between 30°-60° latitude.

Polar Cell

Convection cell located between 60°-90° latitude.

Coriolis Effect

Apparent deflection of moving air (and objects) due to Earth's rotation.

Polar Easterlies

Winds that originate in the east and move from polar high (90°) toward 60° low, deflected right in the Northern Hemisphere.

Westerlies

Winds that move from 30° high toward 60° low, deflected right in the Northern Hemisphere, originating in the west.

Trade Winds

Winds that move from 30° high toward equatorial low (ITCZ), deflected right in the Northern Hemisphere, blowing from northeast to southwest.

Doldrums

Calm, weak winds near the equator (0°) where winds slow and stall.

Pressure Belts

High and low pressure zones that alternate by latitude.

High Pressure (90°)

Cold, dry, desert-like conditions found at the poles.

Low Pressure (60°)

Clouds and rain belts found at 60° latitude.

High Pressure (30°)

Dry, desert regions found at 30° latitude.

Low Pressure (0°)

Warm, rainy tropics found at the equator (ITCZ).

Deserts

Regions found at 30° N/S and 90° (poles), such as the Sahara Desert.

Rain Belts

Regions found at 0° (Equator) and 60° N/S, such as tropical rainforests.

Friction

Slows and deflects winds, caused by mountains, forests, and rough terrain.

Non-uniform surface of Earth

Land heats/cools faster than water, affecting temperature moderation.

Seasonal shifts

Changes in sunlight distribution due to Earth's tilt, moving pressure belts north/south.

January (NH Winter)

Pressure centers include strong Polar Highs and low pressures over oceans.

July (NH Summer)

Pressure centers shift northward with the sun over Tropic of Cancer.

Local Example: Louisiana (30°N)

Humid and rainy due to proximity to Gulf of Mexico and influence of low-pressure systems.

Big Picture: Why This Matters

Prevailing winds and pressure belts control movement of weather systems and local climates.