Parhelion, also known as "sun dogs," is an atmospheric optical phenomenon that occurs when sunlight passes through hexagonal ice crystals in high-altitude cirrus or cirrostratus clouds. These ice crystals, often in hexagonal plate or column shapes, refract sunlight at specific angles. When sunlight enters and exits these crystals, it bends and reflects, creating a halo around the sun and forming bright spots on either side.
Typically, parhelia appear 22 degrees to the left and right of the sun, hence often referred to as "22-degree halos." Due to varying angles of light refraction through the crystals, parhelia display rainbow-like colors, with red closer to the sun and blue or violet on the outer edge.
幻日（Parhelion）是大氣光學現象，當太陽光通過高空中含有六角形冰晶的卷雲或卷層雲時，會產生幻日。這些冰晶通常呈六角柱或板狀，能以特定的角度折射陽光。當光線進入冰晶後經過屈折與反射，形成一個光暈，並在太陽兩側生成明亮的光點。
幻日通常出現在太陽的左右兩側，與太陽呈22度角，因此也被稱為「22度幻日」。由於光線經過冰晶折射的角度不同，幻日會顯現出彩虹般的色彩，其中紅色靠近太陽，而藍色和紫色在外圍
