Subsun

A subsun or sub-sun is a glowing spot that can be seen within clouds or haze when observed from above. The subsun appears directly below the sun, and is caused by its light reflecting off of numerous tiny ice crystals suspended in the atmosphere. As such the effect belongs to the family of halos. The region of ice crystals acts as a large mirror, creating a virtual image of the sun which appears below the horizon, analogous to the sun's reflection in a body of water.