Sun, moon, planet and light pillars

Sun, Moon, Planet, and Light Pillars: A Mesmerizing Atmospheric Phenomenon

Have you ever witnessed a breathtaking display of light pillars in the sky? These captivating optical phenomena occur near sunrise or sunset when the sun is low on the horizon. Pillars of light can extend up to half or even the full width of an outstretched hand at arm's length, creating a truly awe-inspiring sight. While they are often seen after sunset, they can also be observed before dawn, with a bright moon or even a planet. Additionally, you may spot multiple pillars simultaneously over bright lights. Let's delve deeper into this fascinating atmospheric optics phenomenon and uncover the science behind it.

Contrary to their name, light pillars are not physical pillars or beams of light. They exist only in our perception, appearing as vertical columns of light reaching towards the sky. These ethereal structures are a type of ice halo formed by plate-shaped ice crystals floating in high-level clouds such as cirrus, altostratus, or cumulus clouds. These crystals, which have roughly horizontal facets acting as tiny mirrors, reflect sunlight towards our eyes, creating the illusion of a pillar shape. Millions of glints from these crystals combine to form the mesmerizing pillar effect. It's important to note that light pillars are not exclusive to freezing temperatures; they can be found worldwide, although the most spectacular ones often occur during sub-zero temperatures.

The formation of light pillars begins with the presence of plate-shaped ice crystals in the atmosphere. These crystals align themselves horizontally due to downward motions relative to local air currents. While some believe that these crystals fall from the clouds, they actually drift within the cloud and can move in any direction, including upwards. Imperfect and wobbly plates produce the best pillars, as other types of ice halos prefer more perfectly aligned ice. The horizontal alignment of these crystals acts as a series of tiny mirrors that reflect sunlight, resulting in the pillar's appearance.

In some cases, light pillars can extend exceptionally tall, reaching up to a bright upper tangent arc. These unusually tall pillars are formed by columnar ice crystals with their long axes aligned horizontally. This alignment is achieved through the rotation of the crystals around both vertical and horizontal axes. The rotation causes the long side faces of the crystals to spend more time near horizontal angles, creating the near-horizontal mirrors responsible for these unique pillar formations.

While the sun is the most common light source for pillars, any bright light can produce this phenomenon. A bright moon in a dark sky provides an ideal opportunity to observe moon pillars. Even planets like Venus can create pillars when their light interacts with ice crystals in the atmosphere. In colder weather conditions, when there is low-level or ground-level diamond dust (tiny ice crystals), the presence of nearby artificial lights can lead to the formation of multicolored light pillars. The rays of these lights, no longer parallel due to their proximity, produce divergent light pillars and sometimes peculiar halo shapes.

In conclusion, witnessing the beauty of sun, moon, planet, and light pillars is a truly enchanting experience. These optical phenomena, created by the reflection and refraction of sunlight by ice crystals in the atmosphere, add a touch of magic to our skies. Whether it's the mesmerizing columns of light reaching towards the heavens or the intricate patterns formed by these crystals, light pillars never fail to captivate our imagination. So keep your eyes peeled during those golden hours of sunrise and sunset, and you may just catch a glimpse of these celestial wonders painting the sky with their radiant presence.

A sunrise pillar over frozen (-31 C) Alberta, Canada.

The lumpy appearance arises from different concentrations of ice crystals with height.

A brave photo by Sheryl Garrison.

Pillars of the Sky

The Look: Near sunset when the sun is low. Or minutes or even an hour afterwards depending on when you are and the season. Above reaching up to half to even to the whole width of an outstretched hand at arm's length. I enjoy them most after sunset. Then, as twilight ticknens, they creep slowly northwards. Always keeping themselves over where the sun sinks ever deeper beneath the horizon.

See that in reverse before and after dawn. See them with a bright moon or even a planet. See many at once over bright lights.

Pillars, and yet not pillars.

Two Myths: Pillars they are not. Well, perhaps in the mind's eye but never in any real physical sense.

They are never beams of upward or downwards light. You could fly around and chase them in the skies but would never find any light beacons.

Only seen in the freezing weather of northern parts - or the frozen lands far south? No so. Search and you will find them anywhere on the planet.

But itmust be confessed that the finest are suring sub-zero temperatures. Then, their ice crystals authors can descend to ground level as diamond dust that sparkles in the and pricks the skin.

This time a sunset pillar seen in warm May from the Church of Montespineto, near Arquata Scrivia, Italy.

Daaniele Cipollina took the hoto.

Low temperature at ground level are not needed - only the sub-zero temperatures of higher clouds found world-wide.

The Making: They are a form of ice halo. Flattish plate shaped crystals make most - but not all - of them.

The plates float in high cirrus and altostratus or cumulus clouds or as diamonds dust near the ground. Downwards motions relative to local air currents aligns them horizantal. Another myth is that the crystals are falling from the clouds. They rearely do that, they only drift about in the cloud and that can be upwards as well.

The best pillars come from large, imperct and wobbly plates. Other halos prefer more perfect well aligned ice and so pillars are often the only halo seen.

Their roughly horizontal facets are tiny mirrors and glint the sun to us. Millions of glints appears as a pillar shape. The crystals happening to glint in our direction can be at a whole variety of distances and heights.

Peter O'toole imaged this unusally tall pillar topped by an upper tangent arc in County Donegal, Northern Ireland.

Another tall pillar with upper tangent arc. Providence, Rhode Island. Imaged by Mike Cohea.

We sometimes see a few very tall and straight pillars reaching up 22 to a bright upper tangent arc. Columnar crystals floating with their long axes horizontal make the upper tangent arcs. Could the unusual pillars come from the same crystals? It seems counterintuitive - where are the near horizontal mirrors?

The early pioneering 1970s ray tracing research of robert Greenler and colleagues teased out the answers. Column crystals rotate about a verticals axis. Plus they rotate around their horizontal axis along the column.

The two rotations results in the crystal long side faces spending more time near to horizontal than at other angles! Near horizontal wobbly mirrors agains.

Halos in the Swiss Alps by Roger Benoit. There is a bright lower pillar linking the sun and subsun.

The Moon, Planets & other Lights: Any light can make a pillar. A bright moon pillar in a dark sky is the easiest to see. Venus has pillars. Moving back to Earth, we have a predictions for unshielded lights, wasting energy, dazzling, trepassing on neighbours and destroying the stars. In cold weather when there is low or ground level diamonds dust, they also make impressive multicoloured light pillars. Put the lamps nearby and their rays are no longer parallel. We then have divergent light pillars and halos of stragne solidity and sometimes strange shapes.

Left: Upper and lower oillars from the light of Venus by John Gauvreau

Right: Pillar like trumpet shaped halos above artificial lights. Horizontal column crystals at low levels created them. By Jonas Forste

Artificial light pillars from plate crystals. Jari Luomanen captured these in Finland.

The days of flim. A historic photo by John Turtle taken 1962 at Byrd Station, Antarctica.

Upper and lower Moon pillars crossed by the paraselenic circle.

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  • "Sun, moon, planet and light pillars". Atmospheric Optics. Accessed on March 28, 2024. https://atoptics.co.uk/blog/sun-moon-planet-and-light-pillars/.

  • "Sun, moon, planet and light pillars". Atmospheric Optics, https://atoptics.co.uk/blog/sun-moon-planet-and-light-pillars/. Accessed 28 March, 2024

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