❄ Ice halos information and list

What is an ice halo?

Ice halos are some of the visually most impressive, yet less known atmospheric phenomena from the majority of people.
They are often wrongly viewed as lens artifacts from the camera that took the picture. Yet, ice halos are real phenomena that can be seen with the naked eye, though some can be very faint.


Multiple display of common and rare ice halos. Credit: Magnus Edbäck, Borlänge, Sweden. Source: taivaanvahti.fr

They are created when the sunlight reflects, refracts, and scatters in ice crystals suspended in the atmosphere, whether the latter are visible (ice clouds, diamond dust) or invisible to the naked eye. So, an ice halo can appear even in a clear blue sky.
Occasionally, if the moon is bright enough, they can also appear in moonlight, but way more faintly.

What do they look like?

Their aspect depends on the form of the ice crystals, their orientation, the sun’s height, and other factors. How they look can vary very much.

How common are they?

It depends on many factors. Some halos are very frequent - more frequent than rainbows.
On the opposite, some are extremely rare, a spectacle of once in a lifetime.
There are even halos that are yet to be discovered or are almost invisible to the naked eye.

Common ice halos

22° Halo

This is the most common of all the ice halos and can be seen in about one of three days on average.
It looks like a faintly colored ring around the sun.


Credit: Patrick Looß, Großkrotzenburg, Germany, unedited, CC BY-SA 4.0

More in-depth explanation:

[to be completed with more explanations, diagrams and stuff…]

Sundog (or parhelion, plural parhelia)

It is very common too. They can appear individually or by pair, each being on each side of the sun. When they’re bright enough, they kind of look like “mini suns” with a glimpse of reddish color on their side. When they’re fainter, they appear multicolored, like a rainbow fragment.


Credit: Gopherboy6956, Fargo, North Dakota. Taken February 18th, 2009, public domain

More in-depth explanation:

[to be completed with more explanations, diagrams and stuff…]

Circumzenithal Arc

Those are less common than previous halos and appear high in the sky -hence their name- when the sun is at a low altitude.
They look like “reverse rainbows” on top of the sky.


Unknown author, CC BY-SA 3.0

More in depth explanation:

[to be completed with more explanations, diagrams and stuff…]

Unommon ice halos

Circumhorizontal Arc

They are rare. They appear at low altitudes when the sun is very high.
They are among the largest ice halos, and for this reason, are rarely seen complete, more frequently only a fragment.


Mikell Johnson, Lehi, Utah, United States of America, CC BY-SA 3.0

More in-depth explanation:

[to be completed with more explanations, diagrams and stuff…]

Crown flash

This striking phenomenon is a rare, moving, pillar-like light that always appears above a storm cloud.
The current explanation for the light is that the sun reflects its light in aligned crystals suspended in the atmosphere.
As for the motion, the magnetic field from lightning inside the storm would reorient the ice crystals above the storm, quickly changing the shape and brightness of the crown flash.

QuadeM13, Greenwood, Indiana, USA | Alternate link: https://archive.org/details/crown-flash

What about other worlds?

Known halos are 100% dependent on earth’s atmosphere factors, including the atmosphere composition and ice crystals shapes.
Ice halos exist in other planets’ skies as long as they have a compatible atmosphere, including Mars, Saturn, and others. These halos can even be simulated by computer to have realistic depictions of what they should look like!
Here’s a scientific publication about extraterrestrial halos:
EPSC2010-2.pdf (325.1 KB)
A. Farkas Eötvös Loránd University, Institute of Geography and Earth Sciences, Department of Physical Geography, Department of Meteorology, H-1117 Budapest, Pázmány Péter sétány 1/c, Hungary

Mars

The very first picture of an extraterrestrial ice halo has been photographed from the surface of Mars and published on April 02, 2022. It was a faint 22° Halo similar to those who see on Earth.


NASA/JPL-Caltech, taken by Perseverance rover on December 15, 2021

More in-depth explanation and other pictures:

Enhanced image and comparison with the same halo on Earth:



Though Mars’s atmosphere is composed of 95% of carbon dioxide (CO2), the halo was produced by water (H2O) ice crystal, hence the similarity with the common Earth 22° halo.

Venus

Although no picture of halo has been taken yet, a simulation has been made of what some Venusian halos could look like:


Jacob Klee

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