Parry Arc

Several halo effects were seen over a period of 4 hours on this afternoon and for about 15 minutes of that there was one of the best Parry arcs I've seen.

In this composite there is a circumzenithal arc at top, with just a hint of supralateral arc where it touches the circumzenithal.

Below that is the Parry arc, concave to the sun, with an upper tangent arc curving up towards it.

There is hardly any 22 degree halo but there is a sundog each side of the sun.

Light aircraft are quite common round here but remarkably this biplane flew over at just the right moment.

The colour in the Parry arc above the plane is noticeably stronger than the upper tangent below it.

The colour in the circumzenithal arc at top is again noticeably stronger than the Parry arc

Little more than 5 minutes after the top composite the circumzenithal arc and one sundog have strengthened, but the Parry arc is almost gone.

A couple of good sundogs from earlier in the afternoon seemed almoost routine by comparison.

As thicker cloud moved in the finale was this bright sundog with a long streak of cirrus helping to extend its tail into the parhelic circle. The contrail passing in front of the sun almost exactly lined up with its own shadow.

Canon EOS 5D   22nd September 2012
Wiltshire, England

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