Reader Question: What's That in the Sky?

Larry and Gayle Powell of West Linn, Oregon, emailed us recently to ask about this photo. "We were at the Lowell Observatory on May 2," they wrote. "While in the parking lot, we looked up and saw the attached view. It only lasted a moment. Can you explain what this is?"

We couldn't, so we emailed Brian Klimowski, the meteorologist-in-charge of the National Weather Service station in Flagstaff. Here's what he said:

Beautiful picture! Indeed, looks like a good example of iridescent clouds — formed when the sunlight is shining through a thin layer of cloud droplets of a similar size. It looks like a rainbow, but the colors are caused by diffraction of the different wavelengths of light (colors) as they pass through the cloud.

Here's a link to a page that illustrates several examples of iridescent clouds.

Thanks for sharing your photo, Larry and Gayle. And you can learn more about Brian Klimowski's work in an upcoming issue of Arizona Highways.

Photo: Iridescent clouds above Lowell Observatory in Flagstaff. | Courtesy of Larry and Gayle Powell