Experts describe the "light pillars" phenomenon that lit up the night sky in Graceville, Minnesota. As seen on social media, the display put on an amazing show early on Thursday morning.
Carol Bauer recorded the peaceful scene and shared images and videos of the magnificent performance on Twitter.
Light Pillars
When light from the surface of the Earth reflects off the six-sided ice crystals suspended in the frozen clouds above, light pillars are formed.
Michael Kavulich from the National Center for Atmospheric Research said that it resembles a dinner plate, and in extremely calm conditions, they will align themselves horizontally, where they can essentially serve as mirrors.
Each ice crystal will reflect a different color of light, producing an eye-catching display above. Kavulich said that these horizontal ice or mirror crystals are the reason why light pillars appear at night because they reflect the ground-level lights.
Sun Pillars
However, light pillars don't just happen at night; numerous reports of sun pillars have also been made.
The same process that produces ice pillars also produces sun pillars. When the sun shines through a layer of ice crystals that are flat and suspended in the clouds, they can appear at sunrise or sunset.
Kavulich explained that, for instance, between the observer and the sun, there are thousands of tiny mirrors, each one facing horizontally and standing at a different height. Each of these tiny mirrors reflects just a tiny bit of the sun's light, which comes together to form a horizontal column called a pillar.
Kavulich said lower altitudes have calmer conditions that are essential for aligning the crystals.
The Atmospheric Optics states that since artificial light rays are not parallel to one another, plate crystals with slight tilts can still reflect the light downward, allowing artificial light pillars to grow taller than natural ones.
For the pillar to form, the crystals must be approximately halfway between the observer and the light source. According to the Optics website, if it's a cold night and ice crystals are all around the observer, even nearby lights, like streetlights, can emit pillars, FOX Weather reports.
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Predicting Light Pillars
According to AccuWeather Meteorologist David Samuhel, when the temperature is below zero [F] and the ice crystals are the right size. They are small enough to stay suspended in the air. In most cases, it is -10 to -20 degrees or colder outside.
Samuhel claimed that the pillars form in the presence of high pressure but no storm.
Samuhel said that the pillars and storms have nothing in common. The pillar formation would be disturbed by wind and precipitation from a storm system.
The majority of pillars come from man-made sources, like street lights and other types of ground lighting. They vary from auroras in many ways, but auroras are more well-known because they are much more widespread.
Since auroras happen thousands of miles up in the atmosphere, they can be seen over a much wider area. Samuhel emphasized that Light pillars can be found in the lowest parts of the atmosphere, close to the surface.
Samuhel is aware that light pillars are invisible to radars.
He continued by saying that it is likely possible to predict when light pillars will be visible by predicting cold and calm weather. However, predicting the formation of ice crystals is more challenging, AccuWeather reports.
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