Global Circulation: Winds and Earth's Rotation

Introduction

• Atmospheric circulation is divided into three cells in each hemisphere:
  • Hadley Cell
  • Ferrel Cell
  • Polar Cell
• Earth's rotation influences these winds, forming jet streams and prevailing wind patterns.

Coriolis Effect

• Global circulation is angled due to Earth's rotation.
• Coriolis Effect: Apparent motion to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
  • Earth's surface rotates faster at the equator.
  • Affects objects in motion, causing deflection.
  • Winds blow anti-clockwise around low pressure and clockwise around high pressure in the Northern Hemisphere (opposite in the Southern Hemisphere).

Wind Patterns

• Jet Streams: Formed by the deflection of air moving away from the equator.
  • Subtropical Jet Stream: Occurs between 12 to 15 km, reaching high speeds.
  • Polar Front Jet: Formed by temperature contrast at the Polar Front, stronger in winter.
• Trade Winds:
  • Formed by the surface flow of the Hadley cells.
  • Northeast Trade Winds in Northern Hemisphere.
  • Southeast Trade Winds in Southern Hemisphere.
  • Aided historical trade routes.
• Prevailing Westerlies:
  • Occur in Ferrel cells.
  • Deflected by Coriolis effect.

Comparison to Other Planets

• Jupiter has similar circulation cells due to its fast rotation and large size.
• Strong Coriolis effect splits its atmosphere into many cells, causing a striped appearance.