Strange Doings in the Sky Today. What the Heck is a Circumzenithal Arc?

We live our lives never truly knowing when the day comes that something remarkable happens. I was doing totally normal errands today in the middle of town when I saw a sun dog, a common enough occurrence, but it was so bright I decided to snap a shot. But as I got out of the car, I realized something more complex had become visible, something I'm fairly sure I've never seen before. The sun dogs were connected to a halo around the sun, but at the top was an "upside-down" rainbow, like a giant smile in the sky.

I made use of a highly technological sun-blocking tool that I have in my pockets sometimes to try and bring out the colors a little better. In my capacity as an earth science instructor I generally teach about climate and weather, but phenomena related to the refraction of light off hexagonal ice crystals in the upper atmosphere gets lost in the concerns over global climate change and that sort of thing. So I haven't kept up the finer details of atmospheric refraction effects, and had to get a refresher about what I was seeing.

Source: Meteorology Today by Don Ahrens

There were five phenomena happening at once here, all related to the refraction of light in ice crystals in the upper atmosphere: a 22 degree halo, part of a 46 degree halo, two sun dogs, an upper tangent arc, and high above, the circumzenithal arc (the upside-down "rainbow"). I read that the arcs are not uncommon, but are noticed less because they tend to occur overhead where people don't tend to look. I didn't see it myself until I stopped on the way home to try and catch the arc again. It can be seen in the picture below.

Beautiful things can find you any time. You just need to watch for them!
 

About That Bucket List...What Would You Do To See These Places?

Horseshoe Bend on the Colorado River

So...about that bucket list of yours. 

Surely you have one. If you don't, what's keeping you from making one? Here's a version I promoted a few years back (I've made it to around 70% of them so far and feel exceedingly lucky to have been able to do so).

In any case, how many of the following are (or should be) on your personal list? Possibly Grand Canyon, Zion, Bryce Canyon, Arches, Petrified Forest, Capitol Reef, Yosemite, Great Basin, or Canyonlands National Parks? What about Ancestral Pueblo cliff dwellings at places like Bear's Ears or Grand Staircase-Escalante? Finding ancient petroglyphs along the Colorado River? Or searching for dinosaur bones? How would your life be changed if you could somehow do all these things...in one trip? It's possible!

Grand Canyon National Park

There is no place on this planet like the Colorado Plateau. It's hard to find anyplace else on Earth where the crust remained relatively stable for upwards of a billion years, accumulating several miles of horizontal sediments, only to be lifted up rapidly in the last few million. The Colorado River and her tributaries then stripped away much of the sedimentary cover, and cut deep into the underlying metamorphic rocks. Those metamorphic rocks record a violent geologic history of colliding landmasses and mountain-building. The resulting landscape is one of the most beautiful regions imaginable.

Angels Landing Trail in Zion National Park, Utah

The plateau country is a training ground for geologists and earth scientists, and has been since the days of John Wesley Powell and Joseph Ives, who were the first to lead research parties into the region (they didn't "discover" the plateau, of course; Native Americans have known the region for thousands of years). If you are curious about learning geology in this incredible region, you might consider joining us as a student (of any age) on our geology field studies course Geology 191: Geology of the Colorado Plateau, offered under the auspices of Modesto Junior College in Modesto, California. The course is designed to fulfil the curiosity and build the skills of lay geologists and archaeologists as well.

Mesa Arch in Canyonlands National Park

Our field course will be a grand loop through the plateau country, with investigations of the Mojave National Scenic Preserve, Grand Canyon, Zion, Bryce Canyon, Arches, Canyonlands, Petrified Forest, Capitol Reef, Great Basin and Yosemite National Parks, as well as many monuments, including Bear's Ears, Grand Staircase-Escalante, Natural Bridges, Navajo, and Hovenweep. It will be an unforgettable two week trip from June 3-17, 2024, beginning and ending in Modesto, California. Further information will be found soon here and at my school website. 

Petroglyphs on the plateau

It's not a comfortable trip...we travel in school vans (which of course are known for their luxuriousness!), we camp every night, and the days can be hot, windy, cold, or stormy, and we are out in the middle of anything that happens. But we are staying in beautiful places each night, and there are even showers and laundry available every third day or so! Extensive hiking is not required, but there will be many chances to explore the trails in each park and monument.

Petrified Forest National Park

Geology 191 is a 3-semester-unit course. By end of the course, you will be able to see the landscape the way geologists do: by identifying rocks, minerals and fossils, and interpreting the geological history of an area by working out the sequence of events as exposed in outcrops. If you are a science teacher, you will come home with a collection of photographs that illustrate most of the important principles of geology, and a selection of rocks, minerals and fossils that will make a great classroom teaching tool (legally collected, of course; there are many localities outside of protected parks from which to collect samples). You will also gain some mastery of the archaeology and culture of the plateau region, the home of the Ancestral Puebloans, the Fremont people, the Navajo, the Utes, and others.

Canyonlands National Park, Utah

The cost of the trip (still to be officially determined) will be about $1,100 plus the cost of tuition (Currently $46 per unit for California residents, and around $225 per unit for out-of-state residents). The cost includes transportation, food, camp fees, and entrance fees. Participants would want to bring a few dollars along for showers, laundry, and souvenirs.  The food is tasty and plentiful (everyone helps cook and clean!), and the school vans...are vans.

House-on-Fire Ruin, Bear's Ears National Monument

For those of you who live in the Modesto region, we are having an organizational meeting in April which will also be available as a Zoom session. Details will be provided later on.

If you are not in the area, we will be glad to arrange for transportation from nearby airports and train stations (we actually have an Amtrak station in town). Enrollment can be completed online once you are registered with the college (http://www.mjc.edu). Please contact me with any questions you may have.

Bryce Canyon National Park

Hope to see you out there, back of beyond!

The Simultaneous Seasons of California (and a peek at Half Dome)

It was a beautiful Christmas day here in the Central Valley, one of the prettiest I can recall. The storm that blew through yesterday was gone, and the winds were enough to prevent the fog from setting in. I took a walk along the Tuolumne River Parkway Trail in Waterford, and was gifted one of those rarest of things: a clear view of the beautiful Sierra Nevada. And of course it was the moment of three simultaneous seasons of California.

Yes, it's that time of year in California when three seasons occur at once. Sure, the calendar says it's winter and all, and that is certainly true in the high country of the Sierra, buried under feet of snow. But here in the valley, the last leaves are finally falling from the Valley Oak trees along the river, but with the rain has come the promise of spring as the grass sprouts and spreads a layer of green along the bluffs above the Tuolumne River.

The gift of enjoying the panorama of the Sierra Nevada Crest is rare in our valley. Although my little town sits at the very edge of the Sierra Nevada foothills, the mountain range is a tilted block of crust that slopes gently westward. As a consequence, the high peaks of the Sierra Nevada lie 40-50 miles away. The view of the peaks is generally obscured most of the time, for reasons both natural and artificial. In winter, an inversion layer develops that keeps a barrier of fog and mist that prevents any viewing of the mountains. In the summer and fall, dust and smog obscure the view. It is most often at the end of storms that the mountains are revealed in their full glory like they were today.

The Tuolumne River is one of the two main rivers that drain Yosemite National Park (the Merced River is the other. So the view from my trail encompasses much of the roughly 1,000 square miles of the park (for perspective, Yosemite Valley itself is only about 7 square miles). The view above includes most of the high peaks of the park, including the highest (Mt. Lyell). The diagram below, courtesy of CalTopo, provides the names of the peaks seen in the photo above.

Analysis courtesy of CalTopo

Amazingly enough, Half Dome, Sentinel Dome, and El Capitan in Yosemite Valley are also visible! It's true that you cannot see very much of these iconic rocks, but their summits peek out above the intervening ridges. One generally needs binoculars or a powerful zoom to spy them. 

Still not obvious? I've outlined the top of Half Dome below, with the ridge of El Capitan below and slightly right. There is a much better view to be had of Half Dome from about 5 miles south of the trail near the junction of Keyes Road and S. Hickman Road. It's been a bit of fun arguing over the years with people who are absolutely sure that Half Dome can't be seen from the valley for all kinds of logical reasons (the photos of course are photoshopped or whatever, which by the way is not a skill that I have).

In any case, the view was one of the best gifts of this beautiful day. I hope your Christmas and other celebrations were wonderful, and that you have a great new year! Thanks for reading!