Global Atmospheric Circulation - GCSE Geography Revision

Introduction

• Global Atmospheric Circulation: Heat from the equator is transferred globally in three interconnected cells, forming a pattern of atmospheric pressure and winds.
• Tri-Circular Model: Creates global atmospheric pressure patterns and wind systems.

Key Concepts

The Three Cells

1. Hadley Cell

   • Location: Near the equator.
   • Process:
     • Intense heating at the equator causes air to rise, creating a low-pressure zone.
     • Rising air cools, forming cumulonimbus clouds, and moves towards poles.
     • Air cools and sinks at 30°N and 30°S, forming high-pressure zones and deserts.
     • Air flows back as trade winds, deflected due to Coriolis force:
       • Northeast trade winds in the Northern Hemisphere.
       • Southeast trade winds in the Southern Hemisphere.

2. Ferrel Cell

   • Location: Between 30° and 60° latitude.
   • Process:
     • Surface air moves towards poles, forming warm south-westerly (NH) and north-westerly (SH) winds.
     • Winds pick up moisture, meet colder polar air at around 60°N and S.
     • Warm air rises over cold polar air, causing low pressure and unstable mid-latitude weather (e.g., UK weather).

3. Polar Cell

   • Location: Near the poles.
   • Process:
     • Cold air sinks at poles, forming a high-pressure zone (Polar High).
     • Flows towards lower latitudes, meeting warm tropical air at 60°N and S.
     • Creates a subpolar low-pressure zone and polar front, causing unstable weather.

Impacts of Global Circulation

• Wind Patterns: Generated by global circulation, influencing climate and weather.
• Rainfall Distribution:
  • High rainfall in areas like tropical rainforests.
  • Dry conditions in deserts due to sinking air at high pressure zones.

Additional Resources

• Explore related topics and guides on weather hazards, climate change, and geography exam practice.
• Utilize resources like BBC Earth, Quizlet, and Seneca Learning for further study.