Circumzenithal Arc - Yorkshire, England

Last updated on September 16, 2023

Circumzenithal Arc - A Rare Atmospheric Phenomenon in Yorkshire, England

Have you ever looked up at the sky and been captivated by the beauty of the clouds? The atmosphere is full of incredible optical phenomena that can leave us in awe. One such phenomenon is the Circumzenithal Arc, a stunning display of colors that can be seen in the skies of Yorkshire, England. This rare atmospheric event occurs when sunlight interacts with ice crystals in the atmosphere, creating a breathtaking arc of colors that seems to defy gravity.

The Circumzenithal Arc is often referred to as an "upside-down rainbow" due to its shape and positioning in the sky. Unlike a traditional rainbow that forms when sunlight is refracted and reflected by raindrops, the Circumzenithal Arc occurs when sunlight passes through hexagonal ice crystals in thin cirrus clouds. These ice crystals act like prisms, bending the light and separating it into its component colors.

To witness this mesmerizing phenomenon, certain conditions must be met. Firstly, there needs to be a presence of cirrus clouds in the sky. These clouds are thin and wispy, often appearing like delicate brushstrokes against a blue canvas. Secondly, the sun must be relatively low in the sky, usually between 22 and 32 degrees above the horizon. This angle allows the sunlight to pass through the ice crystals at just the right angle to create the arc.

When all these elements align perfectly, a vivid and colorful arc appears in the sky. The Circumzenithal Arc is typically located directly above the sun, forming an arc that reaches high into the sky. The colors of the arc are similar to those of a rainbow, with red on the bottom and violet on top. However, the colors of the Circumzenithal Arc are often more vibrant and intense than those of a rainbow.

The reason for this heightened intensity lies in the way the light is scattered by the ice crystals. Unlike raindrops, which scatter light in all directions, ice crystals have a more selective scattering pattern. This selective scattering allows for the separation of colors and creates a concentrated band of vivid hues in the Circumzenithal Arc.

One of the most fascinating aspects of the Circumzenithal Arc is its rarity. Due to the specific conditions required for its formation, it is not often seen in the sky. However, when it does make an appearance, it is a sight to behold. The arc's fleeting nature adds to its allure, making it a special treat for those lucky enough to witness it.

If you find yourself in Yorkshire, England, keep an eye on the sky, especially on days when cirrus clouds are present. The region's atmospheric conditions make it an ideal location for spotting this captivating optical phenomenon. Remember to look upwards and be prepared to be amazed by the beauty and wonder of the Circumzenithal Arc.

In conclusion, the Circumzenithal Arc is a rare and stunning atmospheric phenomenon that can be observed in Yorkshire, England. Created by sunlight interacting with ice crystals in cirrus clouds, this upside-down rainbow-like arc is a testament to the beauty and complexity of our atmosphere. Its vibrant colors and fleeting nature make it a truly remarkable sight to behold. So next time you find yourself gazing at the sky, take a moment to appreciate the wonders that lie above us, and you might just catch a glimpse of the elusive Circumzenithal Arc.

A circumzenithal arc shines through broken lower level clouds. Captured by Bob Fosbury while in Yorkshire, England during September '00. �Bob Fosbury, reproduced with permission.

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Reference Atmospheric Optics

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