OPOD - Florida Rare halos

Last updated on September 16, 2023

OPOD - Florida Rare Halos: A Spectacular Display of Atmospheric Optics

Have you ever witnessed a mesmerizing display of rare halos in the sky? On November 12th, Nick Beck captured a stunning multiple halo phenomenon in Florida, proving that these ethereal optical wonders can be observed anywhere on the planet, not just in polar regions or during frigid weather conditions.

Beck's experience began as he strolled through downtown Jacksonville and noticed a band of cirrus clouds on the horizon. Intrigued by the peculiar cloud formation, he had a hunch that it could potentially give rise to beautiful halos. His intuition proved to be spot-on.

Initially, the display showcased a weak sundog and segments of the parhelic circle. As the sun climbed to an altitude of 28°, an upper tangent arc, resembling a circumscribed arc, emerged. Additionally, a 22-degree halo and possibly a Parry arc adorned the sky.

However, the true spectacle unfolded when Beck returned home. The halo display escalated to extraordinary levels, featuring a remarkable parhelic circle encircling the horizon. Both 120-degree parhelia and 22-degree parhelia (sundogs) graced the sky. Moreover, an exquisite upper tangent arc and a Parry arc adorned the heavens, with a faint Lowitz arc nestled between them.

Curiously, the sighting of upper Lowitz arcs curving upwards, crossing the upper tangent arc and touching the Parry arc, is exceedingly rare. Prior to the 1980s, no photographic evidence of Lowitz arcs existed, leading to disputes regarding their existence. Traditionally, they were sought after around sundogs. However, the region between the upper tangent arc and Parry arcs appears to be a more fruitful area for their observation.

The occurrence of Lowitz arcs near the upper tangent arc may be attributed to hexagonal column crystals with special orientations, rather than the more commonly observed plate crystals. In a HaloSim ray tracing simulation, columns with 'Parry orientations' were utilized, allowing them the freedom to rock 15° (standard deviation) around a "Lowitz axis." This axis passes through the crystal perpendicular to the prism axis and two face edges. The limited rotational positions around the Lowitz axis restrict the visibility of the arc to its upper region.

Alternatively, if the cloud responsible for halo formation had been more uniform and extensive, Lowitz arcs formed by the traditional plate mechanism might have extended down to the sundogs, presenting a different explanation for their appearance.

This extraordinary halo display in Florida served as a captivating end to a period of scarce halo sightings. The intricate interplay of various atmospheric optics phenomena left spectators in awe, offering a reminder of the astonishing beauty that can be found in the sky above us.

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In summary, this rare halo display in Florida showcased a multitude of optical phenomena, including sundogs, parhelic circles, upper tangent arcs, Parry arcs, and the elusive Lowitz arcs. The presence of these halos outside polar regions and during non-extreme weather conditions demonstrates that atmospheric optics can enchant observers anywhere on Earth. The intricate crystal formations and cloud structures responsible for these halos continue to intrigue scientists and sky enthusiasts alike. So, keep your eyes to the sky, for you never know when you might be fortunate enough to witness a celestial spectacle like the one captured by Nick Beck in Florida.

Florida Rare Halos

Nick Beck caught this high cloud multiple halo display in Florida on 12th November. It helps demonstrate that fine halos can be seen anywhere on the Planet and not purely in Polar regions or during very cold weather.

©Nick Beck, shown with permission

"Yesterday .Saturday Nov 12. I observed a great display with 14 halos! I was walking around downtown Jacksonville and noticed a band of cirrus clouds on the horizon. I had an odd feeling they would make good halos, and I was right.

At first it made a weak sundog, and some segments of the parhelic circle. Then it produced an upper tangent arc .almost a circumscribed arc as the sun was 28° high. and 22 degree halo, and perhaps a Parry arc.

However, when I was back home the display really escalated. A good parhelic circle nearly all the way around the horizon, both 120 degree parhelia and 22 degree parhelia (sundogs).

There was a splendid upper tangent arc and a Parry arc and in between them, a faint Lowitz arc!

I looked at the sky with a convex mirror and there was also a Wegener arc, both sides of the sky, and even a 46 degree halo and both infralateral arcs. Then a faint circumzenithal arc appeared above the large halo. Later the circumzenithal arc reappeared with a supralateral arc.

This was a great day to end a drought of good halos! "

The upper Lowitz arcs curving upwards, crossing the upper tangent arc and touching the Parry arc are a rare sighting. We have no photographs of Lowitz arcs before the 1980s and their very existence was disputed. They are traditionally searched for around the sundogs but the region between the upper tangent (UTA) and Parry arcs might be more fertile ground (sky).

Lowitz arcs localised near the UTA could arise from specially oriented hexagonal column crystals rather than plates. The HaloSim ray tracing simulation at left used 'Parry oriented' columns that were then allowed extra freedom by being allowed to rock 15� (standard deviation) about a �Lowitz axis� passing through the crystal perpendicular to the prism axis and two face edges. Limited rotational positions around the Lowitz axis constrain the visibility of the arc to its upper region. There is another explanation - had the halo forming cloud been more uniform and extensive then Lowitz arcs formed by the traditional plate mechanism might have extended down to the sundogs.

Note: this article has been automatically converted from the old site and may not appear as intended. You can find the original article here.

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