 As they fall through the air, their aerodynamic properties cause them to orient themselves horizontally, i.e., with their hexagonal surfaces parallel to the Earth's surface.When they are disturbed by turbulence, however, the plates start to "wobble", causing their surfaces to deviate some degrees from the ideal horizontal orientation, and causing the reflection (i.e., the subsun) to become elongated vertically.When the deviation is sufficiently large, the subsun is stretched into a vertical column known as a lower sun pillar.