Supralateral arc

A supralateral arc is a comparatively rare member of the halo family which in its complete form appears as a large, faintly rainbow-colored band in a wide arc above the sun and appearing to encircle it, at about twice the distance as the familiar 22° halo.

As in all colored halos, the arc has its red side directed towards the sun, its blue part away from it.

[1] Due to its apparent circular shape and nearly identical location in the sky, the supralateral arc is often mistaken for the 46° halo, which does form a complete circle around the sun at approximately the same distance, but which is much rarer and fainter.

[2] In contrast to the static 46° halo, the shape of a supralateral arc varies with the elevation of the sun.

Before the sun reaches 15°, the bases of the arc touch the lateral (oriented sidewise) sides of the 46° halo.