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Big Horn Layers of Fire

Big Horn Layers of Fire
Big Horn Layers of Fire

Big Horn Layers of Fire

Twilight to me is a night sky in this case, late civil twilight. The 13000 foot high peaks at 130 miles out from my lens. This is a 2 second time exposure and it was very dark out. Once the sun goes down, there is still an hour and a half sky show through the three twilights. You just need a good tripod and time exposures to see the show sometimes. I have photographed many of these from start to finish. This week has been incredible.

Civil Twilight begins about 28 minutes before sunrise or ends 28 minutes after sunset. It is that period from when the sun is about 6 degrees below the horizon. On clear days you can do normal outside activities that require light. That solar elevation angle below the horizon defines each twilight phase. CIvil Twilight is by far the brightest of the three twilights.

Nautical Twilight starts when the sun is 12 degrees below the horizon technically. Both the Horizon AND brighter stars/planets are visible in this twilight. It is the “middle” of the three twilights. At the beginning of Nautical twilight, it’s about one hour to sunrise. Rule of thumb which varies with your position on the globe, is 28 minutes each twilight.

In Astronomical Twilight, If you live in the city, you have probably never noticed astronomic twilight. The are NO shimmers of daylight at the beginning of Astronomic Twilight a full hour and a half before sunrise. . Away from the lights of population centers, we see Astronomic Twilight regularly where there is just a slight greying of the black totally dark sky mid night. It gets as dark here on our ranch in remote northeastern Wyoming as the North Atlantic Ocean according to NASA.

Location: Bliss DInosaur Ranch, Wyoming/Montana borderlands.

Title: Big Horn Layers of Fire

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BigHorn Mountains Cloud Cover

BigHorn Mountains Cloud Cover
BigHorn Mountains Cloud Cover

From My viewpoint at 130 miles out. This area of the sky is the size of your thumb at an arms length on the horizon. The BigHorn Mountains Cloud Cover that night was climbing up the back of the peaks. It was to cover the highest ones within a few minutes of this image collection. I had a visual window to the peaks that lasted at most a few minutes. The sun was still over head and this was very bright and hard to see. The lighting was high overhead and slightly oblique to the images. It’s a tough photographic environment lol.

Getting to see weather move over these 13,000 feet high ridges is a rare treat from this far away.

These huge blocks of the earths crust uplifted during a major tectonic compression episode called the Laramide Orogeny. Cloud peak is 13,175 feet and is visible in this image. The same compressional forces that uplifted the peaks, also downwarped the adjacent basin to the east. This Basin called the Powder River Basin. This basin the major source of coal in the US. The burning of this coal generates 30 percent of the electricity generated in the United States.

My ranch coincidentally sits directly on the western most edge of the Wyoming Black Hills. It is actually JUST east of the edge of the Powder River Basin. If I drive 2 miles west, I start to see alluvial fan sediment. These sediment fans stretch all the way from the Big Horns. Dissected into ridges by huge rivers washing off the peaks during glaciation. . These alluvial deposits are far reaching, called the “Tullock/Fort Union” formation. Major Mountain sized Anticlines and Synclines resulted from the continental wide compression.. Huge were the forces bending even the underlying crystalline Pre-Cambrian rocks. The rocks to clay washing off of those peaks filled the basin and washed just about to my front door.

Location: Bliss Dinosaur Ranch, Wyoming/Montana borderlands.

Title: BigHorn Mountains Cloud Cover

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Twilight Over the BigHorn Mountains

Twilight Over the BigHorn Mountains
Twilight Over the BigHorn Mountains

Twilight Over the BigHorn Mountains is of course a night sky in late civil twilight. The 13000 foot high peaks at 130 miles out from my lens. This is a 2 second time exposure and it was very dark out. Once the sun goes down, there is still an hour and a half sky show through the three twilights. You just need a good tripod and time exposures to see the show sometimes. I have photographed many of these from start to finish. This week has been incredible.

Civil Twilight begins about 28 minutes before sunrise or ends 28 minutes after sunset. It is that period from when the sun is about 6 degrees below the horizon. On clear days you can do normal outside activities that require light. That solar elevation angle below the horizon defines each twilight phase. CIvil Twilight is by far the brightest of the three twilights.

Nautical Twilight starts when the sun is 12 degrees below the horizon technically. Both the Horizon AND brighter stars/planets are visible in this twilight. It is the “middle” of the three twilights. At the beginning of Nautical twilight, it’s about one hour to sunrise. Rule of thumb which varies with your position on the globe, is 28 minutes each twilight.

In Astronomical Twilight, If you live in the city, you have probably never noticed astronomic twilight. The are NO shimmers of daylight at the beginning of Astronomic Twilight a full hour and a half before sunrise. . Away from the lights of population centers, we see Astronomic Twilight regularly where there is just a slight greying of the black totally dark sky mid night. It gets as dark here on our ranch in remote northeastern Wyoming as the North Atlantic Ocean according to NASA.

Location: Bliss Dinosaur Ranch, Wyoming/Montana borderlands

Title: Twilight Over the BigHorn Mountains

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Ucross View to the BigHorns

Ucross View to the BigHorns
Clearmont View to the BigHorns

Surface Geology north of Ucross View to the BigHorns

What a wonderful glacial terrain. The geologist in me sees all sorts of evidence of past glaciers in this valley. Dozens and dozens of “signs”. First of course is the obvious proximity to a 13,000 foot mountain chain. In the last 1/2 million years we have had 5 glaciations advance and retreat in North America (world wide too). We are in an interglacial period at the moment and a mild one fortunately for us. Warm is good, cold means famine historically.

If you look at the valley floor in this scene, note the bumpy nature of the terrain. Each of those bumps is a pile of gravel with all sorts of geomorphological names depending on their shape and relationship to the glacier that was running through this valley. They are all water sorted gravels in various kinds of shapes and sizes. The gravel piles were mostly formed as the glacier receded and left it’s gravel load behind as the ice melted. The geomorphologists out there call glacial gravel “Boulder Clay” because that is pretty much what it is. Boulders and smaller all mixed up.

The rounded mound in the foreground caught my attention. I think (as I didn’t walk out there) that it is bedrock based on the vegetation change at the top. Those upper layers were very hard and resisted the erosion that removed all around it protecting the softer material below. The aforementioned glacier looks like it rode over it giving it that rounded mound like appearance. Classic.

Location: Just outside of Ucross Wyoming

Title: Ucross View to the BigHorns