Home 
  OpticsPOD
  What's New 
  Rays & Shadows
  Water Droplets
  Rainbows
    Not a rainbow!
    Primary
    Secondary
    A's Dark Band
    Other Orders
    Supernumeraries
    Red Bows
    Rainbow Wheel
    Dew Bow
    Sea Spray Bow
    Glass Bead Bows
    Reflection Bows
    Twinned Bows
    Cloud Bows
    Moon Bows
    Image Gallery
    Simulators
  Ice Halos
  High Atmosphere
  Links & Resources
  Search - Index



                 

123456789012345678
   Rainbow Spokes & Wheels  

   
  Saskatchewan rainbow spokes. Larry Phillips pictured this unusual rainbow during a storm late on July 17, 2003.  ©2003 Larry Phillips, shown with permission.   More spokes.
  Shadows in the sky appear by perspective effects to converge towards the antisolar point, which is also the centre of rainbows. When clouds or dense rain showers shadow the light falling into your rainbow cone the shadowed raindrops can no longer send the rainbow's rays towards your eye. The result is one or more dark radial spokes centered on the antisolar point and making the rainbow sometimes resemble a wagon wheel. Bright spokes are similar to anticrepuscular rays except that light is directed into specific directions by large raindrops rather than widely scattered by dust and aerosols.

Sometimes, when clouds are moving fast across the sky, the rainbow wheel appears to rotate.

The brightness of the unshadowed areas illustrate nicely just how much of a rainbow's light is cast inside its rim at deviations larger than the minimum of the rainbow angle.