Uploaded January 2020 | Updated September 2026, 2 weeks ago
That bright curve of colors directly above your head is not an upsidedown rainbow because rainbows only happen in the direction of your shadow, when it’s raining. If you just happened to look up and notice a curve of colors, higher than the sun, then it’s most likely a circumzenithal or circumzenith arc. That’s an arc of color, almost in a circle, at the zenith- the point directly above your head. The ice crystals in clouds bend or refract the light to separate it into the colors of the spectrum.
A halo around the sun, or the two bright spots on either side of the sun, nicknamed sun dogs, signal cirrus clouds- the hint to search for a circumzenithal arc. Even without those, very thin cirrus clouds can still produce a circumzenithal arc.
Circumzenithal arcs are found anywhere on Earth, in any season, when there are cirrus clouds. Sometimes they only last a minute or two, other times they may last hours.
Meteorologist Alan Sealls
Facebook: Alan Sealls Weather
Twitter: @AlanSealls
Web: alansealls.com
en.wikipedia.org/wiki/Alan_Sealls
More educational weather videos for k-12 and even college level by subscription here weatherthings.com/TeacherVideos
That bright curve of colors directly above your head is not an upsidedown rainbow because rainbows only happen in the direction of your shadow, when it’s raining. If you just happened to look up and notice a curve of colors, higher than the sun, then it’s most likely a circumzenithal or circumzenith arc. That’s an arc of color, almost in a circle, at the zenith- the point directly above your head. The ice crystals in clouds bend or refract the light to separate it into the colors of the spectrum.
A halo around the sun, or the two bright spots on either side of the sun, nicknamed sun dogs, signal cirrus clouds- the hint to search for a circumzenithal arc. Even without those, very thin cirrus clouds can still produce a circumzenithal arc.
Circumzenithal arcs are found anywhere on Earth, in any season, when there are cirrus clouds. Sometimes they only last a minute or two, other times they may last hours.
Meteorologist Alan Sealls
Facebook: Alan Sealls Weather
Twitter: @AlanSealls
Web: alansealls.com
en.wikipedia.org/wiki/Alan_Sealls
More educational weather videos for k-12 and even college level by subscription here weatherthings.com/TeacherVideos
