Every-day wonders: the edges of a giant Colorado thunderstorm cell, captured in photo mosaics

By Tom Yulsman | May 22, 2018 11:02 pm

The summer monsoon season in Colorado is still probably weeks away, but we got a spectacular preview today

Northern edge of a giant Colorado thunderstorm cell

An iPhone photomosaic showing the northern edge of a giant thunderstorm cloud that boiled up east and north of Boulder, Colorado today. (Photomosaic:  © Tom Yulsman)

As I was leaving Boulder, Colorado this afternoon, heading for home out on the plains at the foot of the Rockies, I looked up and was stopped short by a giant, glowing thunderstorm cell that was building fast, in all dimensions.

I’ve long been enamored of Western skies. That’s true in all seasons, each of which brings its own wonders. But there’s something particularly special about the cumulonimbus clouds that often boil up in the late afternoon and evening as the warm season gets cooking.

We’re not really in the summer monsoon season yet — it typically doesn’t ramp up in these parts until June or July. But I guess someone forgot to tell that to the atmosphere, which was channeling copious moisture northwards into our region from the Gulf of Mexico, as happens during the summer monsoon.

I love making photographs of our skies, so I pulled over at a spot where I thought I’d get a good perspective on the swelling thunderstorm cell. I only had my iPhone, not my regular rig. But it’s capable of producing quite compelling images.

By this point, the storm was huge. So I took two sets of three images each with my iPhone, one focusing on the northern edge, and the other on the southern one. With each set, I overlapped the images with the idea of using Photoshop later to merge them into a photomosaic.

One of the results of this fun exercise is the image above. Beyond stitching the photos together to create the mosaic, I did some processing, including a little enhancement of contrast overall as well as micro contrast — to bring out some details in the cloud.

Southern edge of a giant Colorado thunderstorm cell.

© Tom Yulsman

Here’s the photomosaic showing the southern edge of the storm.

In stitching the images together, I took a wide view of a three-dimensional scene and reproduced it in a flat, two-dimensional space. That’s a rather abstract way of saying that the top ~third of both images show what was visible directly over my head!

  • carolannie


  • Erik Bosma

    I lived in Alberta for about 20 years from 1976 to 1995. On the highway from Jasper to Edmonton one day, I saw a huge storm cell that seemed to be following the highway at around 40 mph. It looked as if it was way too heavy to be able to stay up in the sky a few thousand feet above me. I came up to it from the trailing edge and after about an hour I came out the front edge. While the rest of the sky was blue this monster was black with an edge of extremely menacing looking roiling clouds. I swore we’d be wrapped up in a tornado at any time but it was just so interesting I couldn’t stop. From a distance it looked like a huge mothership coming in for a landing. When I reached the leading edge the lightning and the hail was so violent I couldn’t see a thing and had to hope the car in front of me knew where he was going. I was so ‘in awe’ I even forgot to take a photo of it although I doubt if my camera would have been able to capture this massive cloud formation.

  • Derpitudinous_Neologism

    It’s a good time of the year, surely.



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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