Requirements to View Light Pillars
The location and appearance of any light pillar depends on 5 factors: The orientation and type of the floating ice crystals, the height of the crystals in the atmosphere, the height of the light source, and the distance of the crystals from the observer.
Also, crystals that are far away from the observer need to have greater tilts, as compared to crystals that are closer, in order for the pillars to be visible.
Light Pillar or Camera Flare?
Although the light pillars appear similar to lens flares in photographs, the only difference being that they can be viewed by the naked eye, while lens flares cannot.
Direction of Light Pillars
When the source of light is close to the ground, the light pillars appear above the ice crystals. But if the Sun or Moon is the source, the pillars can extend below and/or above the crystals.
When ice crystals are close to the observer and illuminated by artificial lights, the pillars that are formed are quite broad. When the crystals are pushed around by the wind, these pillars vanish and reappear, giving the appearance of a shimmering aurora.
Artificial Light Pillars
When the floating ice crystals get clumped together in layers of an ice fog, rather than spreading out evenly, light from artificial sources create bizarre broken light pillars in the air, which often spark UFO rumors. If the ice crystals are in separate layers, multiple light pillars can form at different heights, giving them a very psychedelic appearance.
Interesting Light Pillar Trivia
In extremely cold conditions and still air, light pillars can even be caused from the light emitting from the headlights of a car.
Unique Light Pillar Shapes
In rare cases, the ice crystals may be long and columnar in shape (15 - 20 micrometers across, and between -5 to -25°C), rather than the usual flat hexagonal shapes. This can cause the light pillars to gain a trumpet shape, by flaring towards the ends.
On the other hand, Sun and Moon pillars are visible only when the crystals are tilted at a large angle.
Natural Light Pillars
These pillars can stretch very high, and can acquire the reds, yellows, and purples of the Sun and the clouds near them. In rarer cases, moonlight and artificial light can also form light pillars.
They are known to lengthen/brighten for around 30 minutes after the Sun has gone below the horizon, and depending on the position of the crystals, the pillars may even appear as multiple vertical strips of light instead of just one.
Artificial light pillars can be seen at anytime of the night. Great views can be seen from hills/mountains or an airplane.
Unique Atmospheric Phenomenon
In very rare cases, some ice crystals, form Sun pillars along with Sun dogs, and halos. This happens because of the two-way rotation of the crystals in the air. The sunlight reflects of the end faces of the crystal, when in a horizontal position, producing the pillar.
Rare Light Pillar Sightings
Sun and moon pillars do not necessarily occur only in the cold seasons. This is because even in warm climates, clouds at an high altitude might contain ice crystals. However, such sightings are very rare.
Hunting Lunar Pillars
A lunar pillar can occur during almost all phases of the moon, provided that the atmosphere is icy, the Moon is bright, and the sky is dark.
Planetary Light Pillars
In exceedingly rare cases, light pillars can also be formed by planets such as Venus. To view such pillars, one has to look at the planet when it is close to a clear horizon, after sunset. Also, the air should have a thin layer of cirrus clouds. These light pillars are best viewed with low-power binoculars.