Ice Crystal Halos

Simultaneous upper tangent arc and rainbows

Simultaneous upper tangent arc and rainbows

On 4 June 2011 Pietari Puranen observed these rainbows in Jyväskylä. When he turned around to see the sky around the sun, he observed an upper tangent arc. Remarkably, the arc formed in virga precipitating from the same low clouds around the rainbow forming cumulonimbus. It is rare to see halos in virga so close to rainbows.

As column crystals are formed in temperatures relatively close to 0 degrees Celsius we may assume the Virga has been born in temperatures around, say, -4 to -9 degrees Celcius. At least in those temperatures diamond dust close to the ground seems to most often exhibit column crystals.


  • I have just recently seen a rainbow and noticed that there was a fragment of a CZA,though it was not as great of an example as this display.


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