Seasons Direct result of inclination & parallelism in orbit distribute energy from vertical to oblique rays tilt spreads concentration of energy over broader area

• Summer Solstice (June 22^nd)
  
  
  • Most direct rays (northern hemisphere)
  • Directly overhead (90°) at Tropic of Cancer
  • Longer days, especially northward
    • Above the Arctic Circle - 24 hours light
      
      
• Winter Solstice (Dec 22^nd)
  • Oblique rays, shortest days (northern hemisphere)
  • Directly overhead (90°) at Tropic of Capricorn
    

Equinox (March 21st & September 23^rd)

• Daylight and night-time are equal
• vernal equinox - heading toward summer
• autumnal equinox - heading toward winter

Lines Related to Earth’s Revolution & Tilted Axis

• Arctic Circle
  • On winter solstice furthest limit of sun’s rays (no light)
  • On summer solstice, all above Arctic Circle is illuminated

• Tropics (Cancer & Capricorn)
  • Mark furthest limit the sun is directly overhead
    
    

• A diagram to show where sun is directly overhead on specific date
• in class exercise