We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Circumzenithal Arc?

Mary McMahon
By
Updated Jun 04, 2024
Our promise to you
All Things Nature is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All Things Nature, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A circumzenithal arc is a fascinating atmospheric phenomenon, sometimes called a reverse rainbow, because at first glance it does indeed resemble a backward or upside-down rainbow. Many observers miss out on circumzenithal arcs, because they are located directly overhead; astronomers cite the circumzenithal arc as another reason for people to look up more, as if the stars weren't enough. Unlike a rainbow, which appears opposite the sun, a circumzenithal arc is centered around the zenith of the sky, and can only appear if the solar angle is less than 32 degrees.

In order for conditions to be right for a circumzenithal arc to form, small, flat, six sided ice crystals must be suspended high in the sky to create a field of tiny prisms. The sun's rays enter the ice crystals and reflect through them, projecting an arc in the sky which, if complete, would circle the zenith. Completely circular circumzenithal arcs are rare, however; most of them only take up a section of the sky, looking like a smile looking down from the heavens. The circumzenithal arc will remain until the solar angle changes, unless weather conditions change dramatically.

The colors of a circumzenithal arc are also reversed from those of a rainbow; the violet end of the spectrum is closer to the zenith of the sky, while the red range is closest to Earth. Technically, the red range is still at the top of the arc, but because the arc is reversed, the colors seem upside down as well. When looking at a circumzenithal arc, observers may notice sun dogs, another atmospheric phenomenon, as well, as the conditions that prevail to permit the formation of circumzenithal arcs are also optimal for sun dogs.

In most cases, a circumzenithal arc will last at least half an hour, and sometimes more, plenty of time to admire and photograph the beautiful arc. They are most common in colder climates, where ice crystals tend to collect in the sky with abundance, although they can be seen in temperate zones as well, especially during cooler weather. Just like with a rainbow, it is also possible to see a circumzenithal arc from the inside of an airplane, although it may be difficult to distinguish from a rainbow due to the unique angle the observer is seeing it from.

All Things Nature is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a All Things Nature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
All Things Nature, in your inbox

Our latest articles, guides, and more, delivered daily.

All Things Nature, in your inbox

Our latest articles, guides, and more, delivered daily.