Fog and Atmospheric Optics

Fog with a Glory, Brocken spectre, and two segments of a fogbow.

In the wake of a departing low pressure system I expected that there might be areas of dense fog in the morning. I awoke well before sunrise to look at satellite images to see if fog was developing. And, yes, there were some hints that fog was present. Good!

GOES-16 IR satellite image from ~5 a.m. showing large areas of fog across northern Arizona.
GOES-16 IR satellite image from ~5 a.m. showing large areas of fog across northern Arizona.

I left the house around 6 a.m. and headed east on Lake Mary Road. A few miles outside of town I ran into fog. Visibility dropped quickly to around 1/4 mile. Drive carefully!

My destination was the Mormon Lake Overlook. I had some success last winter at this site with a similar fog situation. As I approached the overlook the fog lifted becoming a low cloud deck above me. Hmmmm….not quite what I wanted. Ahead, I could see the edge of the cloud/fog. As I made the final approach to the overlook the road gained a bit of elevation and, suddenly, I was above the cloud/fog deck. Wonderful.

The sun had not yet risen but it was light enough to see that there was a shallow layer of fog covering the Mormon Lake basin. Moments later the sun began to rise through the dense fog.

Sunrise through the fog.
Sunrise through the fog.
Layers of fog at sunrise.
Layers of fog at sunrise.

With the sunrise a Glory and Brocken spectre became visible. Moments later, two short segments of a fog bow appeared. Also visible is a shadow of the overlook.

Fog with a Glory, Brocken spectre, and two segments of a fogbow.
Fog with a Glory, Brocken spectre, and two segments of a fogbow.
Fog begins to dissipate across the Mormon Lake basin.
Fog begins to dissipate across the Mormon Lake basin.

As the fog began to dissipate over Mormon Lake, I headed towards Anderson Mesa Station (home to several telescopes) because it is high enough to be above the fog. But first, along the way, the road dropped down into the fog and I saw this fog bow.

Fogbow near Lake Mary.
Fogbow near Lake Mary.

Finally, atop Anderson Mesa I once again was above the fog and able to photograph a Glory—this time projected onto trees with autumn colors.

Another glory and Brocken spectre projected onto fall foliage.
Another glory and Brocken spectre projected onto fall foliage.

Finally, here is a time-lapse of the fog over Mormon Lake that includes the Glory and the right-hand side of the fog bow.

Edit: Replaced GOES-16 visibile image with IR image.

Arizona Monsoon Clouds—August 2018

The setting sun lights up rain curtains as a brilliant lightning bolt strikes behind Wukoki Pueblo in Wupatki National Monument.

A previous post displayed photographs of storms and weather that occurred during July of this year’s North American Monsoon. Here are photographs from August (plus the first day of September).

Cumulus and Cumulonimbus

A search for wildflowers and thunderstorms brought me to Rogers Lake west of Flagstaff. It’s a lake only ephemerally during springs with heavy snow runoff. But it makes a grand place for photographs when a wide-open vista is desired. Earlier convective storms were pushing an outflow boundary southward with new convection developing on the boundary.

Outflow boundary and convection over Rogers Lake with the San Francisco Peaks in the distance.
Outflow boundary and convection over Rogers Lake with the San Francisco Peaks in the distance.
A distant cumulonimbus can be seen from the Doney Mountain Picnic Area near Wupatki National Monument.
A distant cumulonimbus can be seen from the Doney Mountain Picnic Area near Wupatki National Monument.
Thunderstorms move across Grand Canyon with low clouds clinging to the higher points and buttes.
Thunderstorms move across Grand Canyon with low clouds clinging to the higher points and buttes.

There was just enough vertical wind shear on this day to allow some storms to briefly exhibit supercell characteristics and deviate to the right —which brought this thunderstorm near the edge of the North Rim of Grand Canyon.

A strong thunderstorm over the North Rim of Grand Canyon is reflected in a small pool of water.
A strong thunderstorm over the North Rim of Grand Canyon is reflected in a small pool of water.
A weak, late afternoon thunderstorm is backlit by the setting sun.
A weak, late afternoon thunderstorm is backlit by the setting sun.

Fog and Smoke

Sometimes the unexpected can be magical. When fog forms in Grand Canyon the visitors may be disappointed but there is the potential for amazing photographs.

A long-lived cluster of thunderstorms east of Grand Canyon pushed a cool, moist outflow into the canyon producing areas of fog near the South Rim.
A long-lived cluster of thunderstorms east of Grand Canyon pushed a cool, moist outflow into the canyon producing areas of fog near the South Rim.
More fog in Grand Canyon.
More fog in Grand Canyon.

Smoke from the Obi Fire on the North Rim produced both amazing and dull conditions.

Smoke from the Obi Fire on the North Rim creates a colorful sunset.
Smoke from the Obi Fire on the North Rim creates a colorful sunset.
Smoke from the Obi Fire fills Grand Canyon and reduces visibility.
Smoke from the Obi Fire fills Grand Canyon and reduces visibility.

Sunset and Full Moon

Sunset after the storms can be amazing. And if there is a nearly full moon, things can get very interersting.

A backlit thunderstorm at sunset over Grand Canyon.
A backlit thunderstorm at sunset over Grand Canyon.
Post-sunset colors illuminate the underside of a dissipating shower.
Post-sunset colors illuminate the underside of a dissipating shower.
Dissipating cumulus clouds at sunset with O'Leary Peak in the distance.
Dissipating cumulus clouds at sunset with O’Leary Peak in the distance.
Dissipating showers are backlit by the setting sun.
Dissipating showers are backlit by the setting sun.
The nearly full moon illuminates the inner canyon as twilight fades behind a distant thunderstorm.
The nearly full moon illuminates the inner canyon as twilight fades behind a distant thunderstorm.
A dissipating thunderstorm anvil cloud is seen above pueblo ruins in Wupatki National Monument at sunset.
A dissipating thunderstorm anvil cloud is seen above pueblo ruins in Wupatki National Monument at sunset.

Rainbows

A double rainbow above Cathedral Rock in Sedona.
A double rainbow above Cathedral Rock in Sedona.
A rainbow, dissipating anvil, thunderstorm, and towering cumulus.
A rainbow, dissipating anvil, thunderstorm, and towering cumulus.

Lightning

And lightning…

An amazing anvil bolt...and too close!
An amazing anvil bolt…and too close!
Lightning west of Sedona, Arizona.
Lightning west of Sedona, Arizona.
Anvil bolt over Cathedral Rock. (It's out of focus—<u>you</u> try focusing in the dark!)
Anvil bolt over Cathedral Rock. (It’s out of focus—you try focusing in the dark!)
Lightning illuminates Grand Canyon at night.
Lightning illuminates Grand Canyon at night.
Lightning strikes the Moenkopi Plateau (composite image).
Lightning strikes the Moenkopi Plateau (composite image).
Several bolts strike behind Wukoki Pueblo in Wupatki National Monument.
Several bolts strike behind Wukoki Pueblo in Wupatki National Monument.
The setting sun lights up rain curtains as a brilliant lightning bolt strikes behind Wukoki Pueblo in Wupatki National Monument.
The setting sun lights up rain curtains as a brilliant lightning bolt strikes behind Wukoki Pueblo in Wupatki National Monument.

It’s early September and the summer monsoon pattern is beginning to fade away. Soon it will be time to start thinking about autumn colors on the peaks.

Grand Canyon Clouds, Fog, and a Moonrise

I have traveled up to the South Rim of Grand Canyon several times in the past few weeks to get interesting weather and cloud photographs.

Fog begins to spill over the rim of Grand Canyon.
Fog begins to spill over the rim of Grand Canyon.

Two weeks ago, we spent two nights at the South Rim waiting for a winter storm to arrive and drop some snow on the higher elevations of the canyon. The storm went too far south and Grand Canyon got nothing but some clouds and a bit of fog. Flagstaff, on the other hand, got about 8″ on snow—which we had to clear from our driveway when we returned.

A thin layer of fog on the South Rim of Grand Canyon.
A thin layer of fog on the South Rim of Grand Canyon.
A zoomed-in view of the fog on the canyon rim.
A zoomed-in view of the fog on the canyon rim.
As the sun rose higher it illuminated the canyon below Hopi Point.
As the sun rose higher it illuminated the canyon below Hopi Point.

The other goal on that trip was to catch the rising nearly-full moon as it climbed above Cape Royal on the North Rim. That worked out well as the clouds had dissipated by late afternoon. This image was shot as a 12-frame panorama (6 across, 2 rows) resulting in an image of ~200 megapixels. There is a lot of detail in the full-resolution image!

Moonrise above Cape Royal, Grand Canyon National Park.
Moonrise above Cape Royal, Grand Canyon National Park.

As the sun fell lower in the sky, shadows raced across the canyon bottom while some of the higher towers and buttes remained in the sun—resulting in some interesting lighting and abstract patterns.

Late afternoon sun in Grand Canyon.
Late afternoon sun in Grand Canyon.
Light and shadow create abstract forms on Cape Royal.
Light and shadow create abstract forms on Cape Royal.

Our final morning had some wave clouds forming downwind of the Kaibab Plateau and being lit by the rising sun.

Wave clouds illuminated by the rising sun.
Wave clouds illuminated by the rising sun.

A few days ago we had a widespread rain event—even though rainfall amounts were not particularly large. Most importantly, measurable rain fell in Winslow. This meant that there was a possibility of fog forming in the Little Colorado River (LCR) Valley and drifting into the eastern reaches of Grand Canyon. I arrived at Lipan Point on the South Rim before sunrise and could see some low-lying fog in the LCR well east of the canyon. As the sun rose and the land began to warm, the fog began to lift and move towards the canyon. Eventually, it reached the Palisades north and east of Desert View Overlook. And, then, it began to spill over the sides evaporating only a short distance below the rim.

A shallow fog layer lies to the east of Grand Canyon at sunrise.
A shallow fog layer lies to the east of Grand Canyon at sunrise.
Fog spills over the rim into Grand Canyon.
Fog spills over the rim into Grand Canyon.

The fog soon swept across Desert View Overlook. I headed over to Desert View to shoot photos of Desert View Watchtower in the fog—but the fog was so thick I had to get very close to even see it.

Fog swirls around Desert Watchtower.
Fog swirls around Desert Watchtower.
And—for just a moment—there was great color in the sky behind Desert Watchtower.
And—for just a moment—there was great color in the sky behind Desert Watchtower.

I went back to Grand Canyon again the next morning but there were clouds along with some drizzle and light rain. However, there was a 2–3 minute period in which some clouds had a bit of sunlight color. Yes—that’s a pretty long round-trip drive for 2–3 minutes of good photography. Nobody ever said it was easy…

Mormon Lake with Fog, Snow, Rime, and a Glory

A winter storm in late February brought hope again of getting some photographs of the San Francisco Peaks covered in snow. So I departed before sunrise one morning to head out towards Mormon Lake. Because of the warm winter up through mid-February, most of Lower Lake Mary and Upper Lake Mary remained mostly ice free. With very cold early morning temperatures it was no surprise that there was fog over the relatively warm open waters of the lakes. When I left my house, the temperature was about +3°F. When I reached Lower Lake Mary, the temperature had fallen to -10°F—and there was considerable fog.

A shallow layer of fog covers Mormon Lake.
A shallow layer of fog covers Mormon Lake.

It was the same over Upper Lake Mary. I debated whether to change my plans and shoot photographs of the fog over this lake but after viewing the scene I chose to continue to the Mormon Lake Overlook. As I approached the overlook, I could see a layer of fog. Luckily, the overlook was just high enough to be above the fog.

It was a beautiful scene with a shallow layer of fog covering the lake bed and snow on the distant San Francisco Peaks.

San Francisco Peaks as seen from the Mormon Lake Overlook.
San Francisco Peaks as seen from the Mormon Lake Overlook.

After getting a few quick photos I set about to capture a panorama. I shot 12 images: 2 rows of 6 shots. The resulting image is huge and clocks in around 190 megapixels. I can make a print of this that’s 8 feet wide. But I probably won’t because I don’t have a wall large enough for something that big.

It was obvious that sometime during the night the fog layer was much deeper as all the grasses, bushes, and trees were covered with rime ice.

Rime ice coats the grasses and bushes.
Rime ice coats the grasses and bushes.
Rime ice coats the grasses and bushes.
Rime ice coats the grasses and bushes.

The rime created needles that pointed in the direction of the light wind that had been present during formation. As the sun rose above the horizon, the rime caught the light and sparkled brilliantly.

A glory and a small segment of a fog bow are visible on the fog layer.
A glory and a small segment of a fog bow are visible on the fog layer.

So we had fog over the lake bed, snow on the mountain, and rime ice on the grasses. What else? Well, a glory became visible as the sun rose high enough to illuminate the fog layer below me. And a short segment of a fog bow was also visible in the fog layer.

Not a bad day for photography.

The Big Fog

Widespread, dense fog covered portions of northern Arizona for more than a week in early December. The fog appeared at Winslow, Arizona (KINW), during the evening of December 3 and finally dissipated on the afternoon of December 12. Similar conditions were experienced in Flagstaff, Arizona (KFLG), with fog appearing on the afternoon of December 4 and finally dissipating in the evening of December 10. For some locations, including Flagstaff, the fog was episodic with periods of dense fog interspersed with clear conditions. Farther to the northeast, including places such as Winslow and the Chinle Valley, the fog was more persistent.

A sea of fog across northern Arizona at sunrise.
A sea of fog across northern Arizona at sunrise.

The fog was the result of a heavy rainfall event across northern Arizona December 2–4. Many locations received between 1 and 2 inches of rain. Following the rain, high pressure developed across the southwest and a strong thermal inversion developed. The inversion was finally removed when a trough moved across the region bringing strong southwest winds and steeper lapse rates.

Visible satellite image showing extensive areas of fog across northern Arizona.
Visible satellite image showing extensive areas of fog across northern Arizona.

It should be noted that thermal inversions are not rare. Quite the contrary. An inversion commonly occurs at night and during the winter when the angle of the sun is very low in the sky. After last years fog event in the Grand Canyon, some in the media declared that thermal inversions are rare and that the inversion was the cause of the fog. Not really. Both then and now the moisture evaporated out of the soils but was trapped near the ground by the inversion. And, slowly but surely, the moisture content of the lowest few hundred meters of the atmosphere became saturated and fog developed.

Well—enough of the meteorological explanation. What did it look like (video)?

When these shallow fog events occur it is possible to find hills and mountains that are above the inversion so that an observer can look down on the fog. This often results in some amazing photographic opportunities. Anticipating that the fog would occur, I was ready to travel to the Grand Canyon to capture images of the fog filling the canyon. Well, it didn’t quite fill the canyon—at least, not like last year. But there were still photographic opportunities.

I also found myself on the lower slopes of the San Francisco Peaks north of Flagstaff and was able to capture images and video of the fog streaming across the pass between the San Francisco Peaks and O’Leary Peak as well as the sea of fog across the Little Colorado River Valley.