Lowitz arcs are three arcs that can be seen at rare occasions. They
are named after its discoverer Tobias Lowitz who observed them during
a spectacular halo display in St Petersburg 1790. The three arcs all
pass through the sundog (parhelion). The lower Lowitz (infralateral)
arc is tangent to the 22° halo below the sundog and the upper Lowitz
(supralateral) arc is tangent to the 22° halo above the sundog.
The third one is is called circular Lowitz (mesolateral) arc and passes
vertically through the sundog.