What's New 
  Rays & Shadows
  Water Droplets
  Ice Halos
    Frequent Halos
    Infrequent Halos
    Multiple Displays
    Other Worlds
    Observing Halos
  High Atmosphere
  Links & Resources
  Search - Index



Sunrise over Saturn's uppermost ammonia-ice cloud deck. Colourful halos from residual ammonia crystals surround the sun as foils to the far more distant rings marching across the sky. The bright B ring's innermost edge is ~18,700 miles above, beneath it is the faint and tenuous C or 'crepe' ring.   The moon at top is Tethys. The painting by meteorologist and artist Jacob Klee is for latitude 26°N Longitude 120°W 1200UT on March 18, 2016.   ©2002 Jacob Klee, reproduced with permission.
Saturn, like Jupiter, is thought to have three main cloud layers. They lie much deeper down in its atmosphere with the pressure already 0.5-1 bar at the uppermost ammonia-ice crystal haze and cirrus layer. An intermediate level of ammonium hydrosulfide is 60 km (37 miles) below that. Water-ice and water droplet clouds are yet another 90 km deeper.

Titan, Saturn's largest moon, could also be a halo candidate. Models of its hazy atmosphere predict methane-ice clouds at its tropopause 40 km above the surface where the temperature is about 73 K
(-200 Celsius).

More about its atmosphere should be learned when the European Huygens probe descends through it in December 2004.
Circular halos produced by three crystal forms of ammonia (top) and water-ice (below).