Sun Halo
| Polish version is here |
Halos are among my favorite atmospheric phenomena. I must admit that the sight of a large, luminous ring with the Sun positioned at its center never fails to leave a lasting impression.
This optical phenomenon occurs when sunlight is refracted by hexagonal columnar ice crystals suspended in the air. When light passes through two side faces of a crystal set at a 60° angle to each other, the minimum angle of deviation is approximately 22°. Due to slight variations in the refractive index across different wavelengths of light, halos can sometimes appear faintly colored. Most of the light refracts at angles slightly greater than the minimum, which is why the halo is brightest near its inner edge and gradually fades outward. Interestingly, light cannot refract at angles smaller than 22°, making the sky inside the halo appear darker than the area outside. This effect is similar to the dark band of sky visible between the primary and secondary rainbows, known as Alexander’s band.
A halo forms when specific types of clouds—such as cirrus clouds composed of ice crystals—are roughly aligned along the observer-Sun line. This phenomenon can also be accompanied by other stunning and fascinating optical effects, including parhelia (also known as sundogs or mock suns).
Observations
February 8, 2024, around 12:15 PM – Jaworzno (Poland), garden
urban environment
This time, the luminous circle created a striking composition with the silhouettes of trees in the background.
A faint section of the upper tangent arc can also be observed.
June 9, 2024, around 11:00 AM – Dąbrowa Górnicza (Poland)
urban environment
Another (almost) full halo—what a magnificent sight!
We walk on Earth, but it's always worth looking up—there are truly fascinating and beautiful things happening up there.
May 11, 2024, around 12:00 PM – Jaworzno (Poland), garden
urban environment
Today, I had the rare chance to see a complete halo around the Sun—an exceptional occurrence, as halos often appear only in fragments. Witnessing this luminous ring made me feel like a spectator of an extraordinary natural spectacle.
The sky was covered with delicate cirrus clouds.
April 27, 2024, around 9:30 AM – Katowice (Poland), city center
urban environment
An almost complete halo, with visible colors—such a sight is quite rare.
To observe a halo more easily, try positioning yourself so that the Sun is hidden behind an obstacle—this helps reduce glare and makes the halo more visible.
September 7, 2020, around 2:00 PM – Jaworzno (Poland)
urban environment
This time, the photograph captures something that might resemble a miniature rainbow. However, we know that rainbows never appear on the same side of the sky as the Sun and require different conditions to form. The fact that this phenomenon appears as an arc centered around the position of the Sun—hidden behind a spruce tree—confirms that it is indeed a halo.
We can only see a fragment of the halo, but halos typically appear as colorless, white rings—so the beautiful colors in this case more than make up for its partial appearance.
April 30, 2020, around 10:00 AM – Jaworzno (Poland)
urban environment
Although only a fragment of the halo was visible this time, the sight was particularly striking because the phenomenon displayed distinct colors.
Despite the limitations of a quick photograph taken with a phone camera, faint but distinct colors can be seen: the inner part of the arc appears more reddish, while the outer edge is bluish.
April 24, 2020, around 12:00 PM – Bielsko-Biała (Poland)
urban environment
This halo was a surprise since the sky seemed almost cloudless that day.
In this case, the halo likely formed due to ice crystals dispersed evenly throughout the atmosphere, creating a uniform haze rather than distinct clouds.
October 8, 2019, around 9:00 AM – Zabrze (Poland)
urban environment
While braving the cold on my way to the university, I glanced at the sky with hope, having noticed characteristic cloud formations. I was not disappointed—just before entering the building, I was able to admire a well-defined halo around the Sun.
June 22, 2019, around 11:00 AM – Jaworzno (Poland), garden
urban environment
A layer of thin clouds, primarily composed of high-altitude cirrus clouds, created the perfect conditions for observing this phenomenon from my garden in the late morning hours.
Remember: keep your head up! There are truly fascinating things happening up there!
In the past, halos were often seen as signs from a higher power—frequently as foreboding omens.
Marek Ples