Halo

  • a ring of light encircling and extending outward from the sun or moon
  • created as sunlight is refracted as it passes through ice crystals.
  • indicates cirriform clouds (high, thin clouds composed of ice crystals)
  • two types:
    • 22 halo - refraction of light through randomly falling ice crystals.
    • 46 halo - refraction of light through hexagonal column-type ice crystals.
  • here is a 22 and 46 halo

photo by N. Atkins