Mountain Wave Clouds Catch Fire at Sunset

By Tom Yulsman | January 7, 2015 12:42 am
mountain wave

Mountain wave clouds over the Front Range of the Rockies on the University of Colorado, Boulder campus on January 6, 2015. (Photo: © Tom Yulsman)

Pics of the Day

The setting sun conspired with some spectacular cloud formations this evening (Tuesday, Jan. 6th) to put on quite a fireworks display — perfect for the next installment of ImaGeo’s new Pic of the Day feature.

I think what we’re seeing here is a classic example of a phenomenon known as mountain waves. It happens when relatively brisk winds blow across a mountainous barrier.

The mountains you see in the photograph above are actually the foothills of the lofty, elongated Front Range in Colorado, just to the west of the University of Colorado, Boulder. (That’s the main quad in the foreground.)

Winds blowing over mountains like these are displaced upward, and then accelerate downhill on the lee side. This can cause standing waves to form in the airflow, much like a standing wave forms in the lee of a rock in a rapidly flowing stream. And if there’s sufficient moisture, a cloud will form at the crest of the wave.

mountain wave

A standing mountain wave cloud over the foothills near Boulder, Colorado, on the morning of Jan. 6, 2015. (Photo: © Tom Yulsman)

Steady, fast airflow can cause mountain wave clouds to linger for awhile. In fact, I shot the elongated cloud in the photograph above at about 10:30 a.m. So it looks like a cloud-forming mountain wave was in place for quite some time today.

I’ve shared other imagery about this phenomenon before, including this post with an animation of satellite images showing mountain wave clouds forming and dissipating over Nevada. And you can find a detailed explanation of the phenomenon here.

  • Kenny Chaffin

    I saw that! :)

  • Beel

    Very nice, Tom. I got some good shots as well from the soccer fields.



ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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