July 3, 2007

Oh Beautiful for Rainbowed Skies: Rare Horizontal Rainbow Over Oregon

Seen outside of Elgin, Oregon on the Hell's Canyon Scenic Byway, spanning the sky, this rare horizontal rainbow.

Here's a close up.

Here's another.

Seeing this appear in the sky stopped the day. On the other hand, it didn't exactly appear. It was there before it was pointed out. Still, it was an amazing moment; one of those instants in which what you see is so beyond what you know that you sense you are in the presence of the miraculous. Along the road under this rarest of the rainbows, people were pulling their cars and trucks to the side and getting out with whatever photo equipment they had and aiming it at the sky.

Of course, you cannot capture anything that fills the large western sky in a small digital box, but you can, in essence, take note -- in all senses of the word. But still you try. Here's a few of the many pictures I took.

As with most things miraculous, there is a current scientific explanation for the phenomenon. In this case, it is a rare seldom seen rainbow that occurs when conditions are just right. Wikipedia gives it the name "Circumhorizontal Arc:"

"A circumhorizontal arc or circumhorizon arc (CHA), also known as a fire rainbow, is a halo or an optical phenomenon similar in appearance to a horizontal rainbow, but in contrast caused by the refraction of light through the ice crystals in cirrus clouds.

It occurs only when the sun is high in the sky, at least 58° above the horizon, and can only occur in the presences of cirrus clouds. It can thus not be observed at locations north of 55°N, except occasionally from mountains.

The phenomenon is quite rare because the ice crystals must be aligned horizontally to reflect the high sun. The arc is formed as light rays enter the horizontally-oriented flat hexagonal crystals through a vertical side face and exit through the horizontal bottom face. It is the 90° inclination that produces the well-separated rainbow-like colours and, if the crystal alignment is just right, make the entire cirrus cloud shine like a flaming rainbow.

Another reference notes: "The arc is a very large halo and is close to, and parallel to the horizon. Usually only fragments are visible where there happen to be cirrus clouds." In other words a rainbow so big that it rolls right on out of the sky.

Still another sighting via National Geographic News adds:

"The arc isn't a rainbow in the traditional sense -- it is caused by light passing through wispy, high-altitude cirrus clouds. The sight occurs only when the sun is very high in the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to the ground."

All perfectly explained and easily understood. In retrospect. The actual sighting held, and still holds, in my mind as a close contact with the continuing miracle of the world and universe as it unfolds around us. Reflecting on it now it brings to mind a small poem I read long ago by the greatest living poet of the American land, Gary Snyder:


almost at the equator
almost at the equinox
exactly at midnight
from a ship
the full


in the center of the sky.

"Once only." Every moment in life is delivered to us "once only," filled with the enduring mystery and miracle of creation. We know this deep inside us always. But sometimes it takes a rainbow roof painted on the sky to remind us.

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Posted by Vanderleun at July 3, 2007 9:48 PM | TrackBack
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"It is impossible to speak in such a way that you cannot be misunderstood." -- Karl Popper N.B.: Comments are moderated and may not appear immediately. Comments that exceed the obscenity or stupidity limits will be either edited or expunged.

I was driving north on I-5 (north of Portland OR, south of Longview WA) and saw a rainbow appearing to end on a car ahead and one lane to the left of me. This worked for the center and right lanes, for 5-10 minutes.

Never saw a horizontal one, though.

Posted by: Sam L. at July 4, 2007 7:53 AM

I once saw one of those in the sky over Enumclaw, around 1992. There weren't any visible clouds that I could see, though. Unfortunately, the picture I took has long since disappeared. Thanks for sharing these; there may be a logical explanation, but it still takes the breath away.

Posted by: Juliec at July 4, 2007 10:41 AM

On day in college, I happened to look up... and stopped dead, looking at the rainbow straight up. Circumzenital arc (similar to the circumhorizontal arc.)

Thank God I didn't care what I looked like. I just stood there with my head up for several minutes.

Posted by: B. Durbin at July 4, 2007 12:29 PM

So true. A fire rainbow, rain falling while sunshine warms your face, a shooting star, the deeply resonating sound of acappella singing in a tiny Russian chapel, the calving of ice off gigantic blue glaciers, and oh so much more. Transcendant beauty and miracles all about us if we but have eyes to see and hearts to accept.

Thanks for this reminder, Gerard.

Posted by: Jimmy J. at July 4, 2007 2:55 PM

Love this! According to the Bible, the rainbow is God's way of assuring us His covenants are authentic. We are living in interesting times. A very rainbow in a very unique moment, indeed.

Posted by: daughter of patriots at July 8, 2007 12:40 PM

It was late summer 1981 and I was working as an electronics tech for a company supporting lightning research for the USAF as they moved from metal-skin aircraft to fiber-skin aircraft.

We took a 10 meter aluminum 'lightning strike object' (LSO) to South Baldy Peak (~10,700-ft) in Cibola National Forest near Socorro, NM and working with students and staff from the New Mexico Institute of Mining & Technology and a french team of scientists we launched about 30 rockets into storm clouds trailing wires (ala Franklin) to induce lightning to strike our LSO.

On one clear day we all observed something I have never seen since - a circular/halo rainbow. It lasted over 20 minutes and was one of the most beautiful things I have ever seen in my life and travels.

Thanks for the article and photos. Cheers!

RileyD, nwJ

Posted by: Riley D. Driver at July 8, 2007 2:21 PM

I live in Cumbria, The Lake District, UK. Incredibly I have seen 2 very bright horizontal rainbows directly above me. They were not huge but sort of "this is for you rainbow" very weird to see especially when there is no rain and not much in the way of cloud.
Its a miracle alright and I'm on the lookout for the third one on its side! Its a fantastic encouragement booster when things are rough...

Posted by: Chris L at July 10, 2007 2:29 PM

On saturday 28th July 2007 my family and I
saw a horizontal rainbow to the east of Crieff
Scotland. The sky was heavily covered in cloud and the rainbow was very deep. An amazing sight.
There were no cirrus clouds and very little blue patches of sky visible

Posted by: Duncan Brown at July 30, 2007 1:16 PM
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