Published in Weather 28, 258-259 in 1973
G. P. Können
A double tangent arc was observed above the setting sun and photographed with a 17-mm lens. The mutual distance between the arcs was 1.7°. The distance to the sun of the lower component of 21.5° indicate that it is an ordinary tangent arc to the 22° halo. The upper component might have been either a tangent arc to the 24½° halo or a Parry arc II. The shape and distance to the sun rules the first possibility out.