3.1 Global atmospheric circulation patterns

Global atmospheric circulation patterns shape Earth's weather and climate. These patterns arise from temperature differences between the equator and poles, creating pressure gradients that drive air movement. The Coriolis effect, caused by Earth's rotation, further influences these patterns.

Three main circulation cells form in each hemisphere: Hadley, Ferrel, and Polar. These cells, along with solar radiation and regional factors, create distinct wind patterns and pressure systems that play a crucial role in global climate dynamics.

Global Atmospheric Circulation Drivers

Temperature and Pressure Gradients

Top images from around the web for Temperature and Pressure Gradients

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

• 

  Global scale circulation View original

  Is this image relevant?

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

1 of 3

Top images from around the web for Temperature and Pressure Gradients

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

• 

  Global scale circulation View original

  Is this image relevant?

• 

  Atmospheric circulation - Wikipedia View original

  Is this image relevant?

• 

  Global Atmospheric Circulations | Physical Geography View original

  Is this image relevant?

1 of 3

• Uneven solar heating of Earth's surface creates temperature and pressure gradients driving global atmospheric circulation
• Maximum solar intensity occurs at the equator, minimum at the poles
• Differential heating leads to variations in air density and pressure
• Rising air in intensely heated areas (equatorial regions) forms low-pressure systems
• Sinking air in cooler areas (polar regions) forms high-pressure systems
• Resulting pressure gradients between warm and cool regions generate wind patterns
• Global pressure gradient force between equator and poles drives air movement

Earth's Rotation and Energy Transfer

• Coriolis effect from Earth's rotation influences direction of atmospheric circulation patterns
• Latent heat release through condensation and precipitation contributes to atmospheric energy transfer
• Seasonal variations in solar radiation intensity affect strength and position of pressure systems and wind patterns

Regional Modifications

• Topography modifies global circulation patterns on regional scales
• Land-sea temperature contrasts alter circulation locally
• Pressure differences vary based on surface features and temperature distributions

Solar Radiation's Role in Wind Patterns

Solar Energy Distribution

• Solar radiation provides primary energy driving atmospheric circulation
• Differential heating creates temperature gradients across Earth's surface
• Equatorial regions receive more direct sunlight, leading to greater heating
• Polar regions receive less direct sunlight, resulting in cooler temperatures
• This uneven heating establishes a temperature gradient from equator to poles

Pressure System Formation

• Areas of intense solar heating experience rising air, creating low-pressure systems (thermal lows)
• Cooler areas experience sinking air, forming high-pressure systems (thermal highs)
• Examples of thermal lows include the Intertropical Convergence Zone (ITCZ) and monsoon troughs
• Examples of thermal highs include subtropical high-pressure cells and polar highs

Wind Generation

• Pressure gradients between warm and cool regions generate wind patterns
• Air moves from high-pressure to low-pressure areas, creating winds
• Strength of winds depends on the magnitude of the pressure gradient
• Local and regional wind systems develop due to differential heating (sea breezes, mountain-valley breezes)

Global Circulation Cells and Locations

Hadley Cell

• Operates between equator and approximately 30° latitude in both hemispheres
• Characterized by rising air at equator and sinking air at 30° latitude
• Creates trade winds blowing towards equator at surface level
• Forms Intertropical Convergence Zone (ITCZ) where trade winds converge
• Subtropical high-pressure belt develops at 30° latitude where air descends

Ferrel Cell

• Located between 30° and 60° latitude in both hemispheres
• Characterized by rising air at 60° latitude and sinking air at 30° latitude
• Creates prevailing westerlies at surface level in mid-latitudes
• Facilitates formation of mid-latitude cyclones and anticyclones
• Interacts with Hadley and Polar cells, influencing weather patterns

Polar Cell

• Extends from approximately 60° latitude to poles in both hemispheres
• Characterized by rising air at 60° latitude and sinking air at poles
• Creates polar easterlies at surface level near poles
• Forms polar front where it meets Ferrel cell
• Contributes to formation of subpolar low-pressure belt at 60° latitude

Coriolis Effect on Circulation Patterns

Fundamental Principles

• Coriolis effect caused by Earth's rotation deflects moving air
• Deflection occurs to the right in Northern Hemisphere, left in Southern Hemisphere
• Strength varies with latitude, strongest at poles and weakest at equator
• Combines with pressure gradients to create geostrophic balance
• Geostrophic balance explains air flow parallel to isobars in upper-level circulation

Influence on Wind Systems

• Affects direction of major wind systems in global circulation cells
• Contributes to formation of easterly trade winds in Hadley cell
• Influences development of westerlies in Ferrel cell
• Shapes polar easterlies in Polar cell
• Impacts formation and movement of large-scale weather systems (hurricanes, mid-latitude cyclones)

Applications and Importance

• Critical for accurate weather prediction and climate modeling
• Explains spiral patterns in cyclonic and anticyclonic systems
• Influences ocean currents, affecting global heat distribution
• Considered in planning flight paths and missile trajectories
• Understanding Coriolis effect essential for meteorologists and climatologists