Subsun, China - OPOD

Last updated on September 16, 2023

The Subsun Phenomenon: A Dazzling Display in the Skies of China

Have you ever looked up at the sky and been amazed by the incredible optical phenomena that can occur? One such phenomenon, known as a subsun, was recently witnessed by Qianzhengrong during a flight from Beijing to Chengdu in China. This captivating event was captured in photographs, showcasing the breathtaking beauty of nature's wonders. In this article, we will delve into the details of the subsun phenomenon, exploring its causes and the mesmerizing effects it can create in the sky.

What is a Subsun?

A subsun is a remarkable atmospheric optical phenomenon that occurs when sunlight is reflected by plate crystals suspended in the air. These plate crystals, which are found in clouds, reflect the sun's rays from their upper and lower near horizontal faces. The reflection is further enhanced when these crystals wobble slightly, causing an enlargement of the reflected light. This creates a stunning visual effect, with the subsun appearing as a bright spot in the sky.

The Enigmatic Beauty of Plate Crystals

Plate crystals play a crucial role in the formation of subsuns. These tiny ice crystals are hexagonal in shape and possess upper and lower faces that act as mirrors for the sun. As sunlight passes through these crystals, it is refracted and reflected, resulting in the creation of various optical phenomena. The subsun, in particular, appears at the same distance below the horizon as the sun is above it, adding to its ethereal allure.

The Brilliance of a Subsun

One of the most striking aspects of a subsun is its sheer brightness. These phenomena can be shockingly bright, captivating viewers with their luminosity. The intensity of the subsun's brilliance is a result of the countless plate crystals reflecting sunlight simultaneously. As light passes through these crystals and undergoes multiple reflections, it becomes concentrated, leading to a dazzling display in the sky.

Unveiling the Subparhelion

During the same flight, another intriguing phenomenon was observed: a subparhelion. Similar to the subsun, the subparhelion is caused by the reflection of sunlight by plate crystals. However, unlike the subsun, which appears as a bright spot below the horizon, the subparhelion appears as a bright spot above the horizon. This creates a captivating contrast in the sky, further enhancing the overall spectacle.

Exploring Bottlinger's Rings

When observing a subsun, it is worth examining the surrounding area for rare Bottlinger's rings. These rings, named after German physicist Carl Bottlinger, are circular halos that can sometimes be seen around the subsun. They result from light passing through the plate crystals at specific angles and being refracted in a manner that creates concentric rings of color. The presence of Bottlinger's rings adds an extra layer of intrigue to the already mesmerizing subsun phenomenon.

A Journey Through the Clouds

The flight from Beijing to Chengdu offered a unique opportunity to witness multiple atmospheric optical phenomena. After encountering the subsun, the plane flew into another cloud mass, where a 22° halo and sundogs became visible. The 22° halo is a circular ring of light that appears at an angle of approximately 22 degrees around the sun or moon. Sundogs, on the other hand, are bright spots that can be seen on either side of the sun, caused by the refraction of sunlight through ice crystals in the atmosphere. These additional phenomena added to the awe-inspiring experience of witnessing nature's artistry in the skies.

In conclusion, the subsun phenomenon witnessed during the flight from Beijing to Chengdu in China provided a captivating glimpse into the world of atmospheric optics. Through the reflection and refraction of sunlight by plate crystals, a subsun appeared as a brilliant spot in the sky, accompanied by the enchanting presence of Bottlinger's rings. This celestial spectacle, along with the subsequent sighting of a subparhelion, highlighted the mesmerizing beauty that can be found in the heavens above. The experience serves as a reminder of the remarkable wonders that nature has to offer, inviting us to gaze upwards and marvel at the extraordinary phenomena that unfold in the atmospheric canvas.

Subsun, China

Sighted by Qianzhengrong, , on a flight from Beijing to Chengdu.

Later, a subparhelion (image below) appeared. Afterwards the plane flew into another cloud mass and a 22° halo and sundogs were visible.

Images ©Qianzhengrong

Subsuns are sometimes shockingly bright. This one was.

Plate crystals are responsible. Untold millions of them reflect the sun from their upper and lower near horizontal faces.

The reflection is enlarged when the crystals wobble slightly. Even larger wobbles generate a lower sun pillar. There are vestiges of a pillar in the photograph. Some clouds above and below the subsun are suspiciously bright.

Look carefully around a subsun for rare Bottlinger's rings.

Both upper and lower hexagonal faces mirror the sun.

The solar reflection appears the same distance below the horizon as the sun is above it.

A subparhelion appeared later.

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