OPOD Dutch Lowitz Display

OPOD Dutch Lowitz Display: A Rare Atmospheric Optics Phenomenon

Have you ever witnessed a mesmerizing atmospheric optics display? Imagine driving along the A12 near the town of Ede, The Netherlands, on a day filled with cirrostratus clouds. This is exactly what Hans Nienhuis experienced on September 29, '10. Throughout the day, he noticed the presence of sundogs, which are bright spots on either side of the Sun. However, something extraordinary happened just before half past five in the evening. The left sundog started to rapidly grow and became one of the brightest sundogs observed that year. But that was not all; right next to it, a peculiar phenomenon known as Lowitz arcs appeared, creating a captivating sight in the sky.

Lowitz arcs are a rare ice halo display that often accompanies sundogs. Although the existence of Lowitz arcs was doubted until the 1990s, Hans Nienhuis's photographs provided crucial evidence for their presence. These arcs are named after their discoverer, Johann Tobias Lowitz, who first reported them in 1790. The display consists of three arcs: an upper arc, a middle arc, and a lower arc. However, it is more common to observe either the upper or lower arcs extending from a sundog. Witnessing all three arcs simultaneously, as captured in Hans Nienhuis's images, is relatively rare.

The formation of Lowitz arcs is believed to occur when plate-shaped ice crystals take up different rotational orientations about a near-horizontal axis passing through two opposite vertices of a hexagonal prism. This orientation creates three possible ray paths between faces inclined at 60 degrees, giving rise to the three distinct arcs. However, the current model does not fully explain all the intricacies observed during a Lowitz arc display. It often struggles to reproduce the finer details and variations seen in these phenomena.

To better understand the physics behind Lowitz arcs, researchers have utilized ray-tracing simulations. In one particular simulation called HaloSim, the red rays were traced to generate a representation of a Lowitz arc display. Interestingly, this simulation required unusually thick ice plates with a length-to-width ratio (c/a) of at least 0.3 and some irregular hexagonal shapes to produce a bright enough middle arc. These findings highlight the complexity of Lowitz arc formation and the challenges in accurately reproducing these phenomena through modeling.

Hans Nienhuis's photographs provide a unique perspective on Lowitz arcs, showcasing their beauty and intricacy. The images depict the lower Lowitz arc clearly, demonstrating its presence alongside the other arcs. Such detailed visual documentation helps researchers and enthusiasts alike in studying and appreciating these captivating atmospheric optics displays.

In conclusion, witnessing a Lowitz arc display is a rare and awe-inspiring experience. The combination of sundogs and these distinct arcs creates a spectacle that captures the imagination. Thanks to photographers like Hans Nienhuis, we have been able to gain valuable insights into the formation and characteristics of Lowitz arcs. However, much remains to be discovered about these fascinating atmospheric phenomena, and further research and observations are necessary to unravel their mysteries fully. So, keep your eyes on the sky, for you never know when you might encounter the enchanting dance of Lowitz arcs.

All three Lowitz arcs ~ A rare ice halo display seen by Hans Nienhuis on September 29, '10.

"I was driving along the A12 near the town of Ede, The Netherlands. For the whole day there had been cirrostratus all over the sky, sometimes with a glimpse of one of the two sundogs. Nothing special seemed to happen - just a display with sundogs as seen so often before.

But just before half past five, when I looked up towards the sun again, the left sundog started to grow rapidly. Finally it became one of the brightest sundogs of this whole year. A few minutes later the sundog started to decay. But right next to it something else had appeared.

Lowitz arcs? There was no sign of the 22� halo at all and right between the sundog and the sun, there was a kind of a 'gap' in the bows. Then right in front of the car there started a traffic jam. This was the first time ever that I was glad of a traffic jam. It gave me enough time to find my camera and to take some pictures through the car windows before it was too late!"

Images ©Hans Nienhuis, shown with permission.

The first publicly reported photographs of Lowitz arcs were taken as recently as the 1990s. Until then, and even afterwards, the arcs' existence was in doubt.

There are three Lowitz arcs, 'upper', 'middle' and 'lower' but usually only the upper and/or lower arcs are seen extending from a sundog.

Images like this one showing all three arcs are comparatively rare.

Lowitz arcs are thought to arise when plate crystals take up different rotational orientations about a near horizontal axis passing through two opposite hexagonal prism vertices. There are then three possible ray paths between faces inclined at 60°. These give the three arcs.

The model is not fully satisfactory and often has difficulty in reproducing the finer details of a display.

The HaloSim ray tracing here (for red rays only) needed unusually thick plates (c/a at least 0.3) and some non regular hexagons to generate a bright enough middle arc.

The lower Lowitz is clear in this image

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Reference Atmospheric Optics

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  • "OPOD Dutch Lowitz Display". Atmospheric Optics. Accessed on March 29, 2024. https://atoptics.co.uk/blog/opod-dutch-lowitz-display/.

  • "OPOD Dutch Lowitz Display". Atmospheric Optics, https://atoptics.co.uk/blog/opod-dutch-lowitz-display/. Accessed 29 March, 2024

  • OPOD Dutch Lowitz Display. Atmospheric Optics. Retrieved from https://atoptics.co.uk/blog/opod-dutch-lowitz-display/.