noun
parhelic circle
A rare atmospheric optical phenomenon: a white horizontal circle at the same altitude as the sun, caused by reflection of sunlight from ice crystals.
幻日環は、太陽と同じ高さに現れる白い光の輪です。
A parhelic circle is a white ring of light that appears at the same altitude as the sun.
幻日 (parhelion/sun dog) is a bright spot on the parhelic circle, while 幻日環 is the entire circle itself.
Compound of 幻日 (parhelion) + 環 (ring/circle). The exact historical derivation is uncertain; the term is a modern scientific coinage for the atmospheric phenomenon.