Sunset Parry & Tangent Arcs, The Netherlands - OPOD

Last updated on September 16, 2023

Sunset Parry & Tangent Arcs, The Netherlands - OPOD

The Netherlands is known for its stunning atmospheric phenomena, and on December 7th, 2015, the Dutch skies treated observers to a mesmerizing display of ice halos. During sunset and even after the sun had dipped below the horizon, a captivating double 'V' of upper Parry and tangent arcs adorned the sky.

The Formation of Parry and Tangent Arcs

Both the upper Parry arc and the lower tangent arc are created by hexagonal columns drifting within high cirrus clouds, with their long axes positioned horizontally. However, the similarities between these arcs end there. Let's delve into the details of their formation.

• Tangent arcs are formed by hexagonal columns with random rotational positions around their long horizontal axis. It is worth noting that the individual crystals within these columns may not necessarily rotate.
• On the other hand, Parry arcs are created by columns that, for reasons yet unknown, do not have random rotations. Instead, they keep their uppermost prism side face horizontal. This unique orientation is quite rare, making Parry arcs a relatively uncommon phenomenon. Interestingly, only a few Parry-oriented crystals are needed to produce a vibrant halo.

The Captivating 'V' Formation

Several minutes after the sun had set at ground level, an extraordinary sight unfolded in the high clouds that contained the halo-forming ice crystals: they were still bathed in sunlight. Under these conditions, the Parry and tangent arcs nearly coincide at the bottom of the 'V' shape they create but separate as they extend higher up into the sky. This phenomenon adds an extra layer of allure to an already breathtaking display.

A Visual Delight

The photographs captured during this event perfectly showcase the ethereal beauty of these atmospheric optics. The vibrant hues of the setting sun contrasted with the delicate ice crystals, creating a spectacle that captured the attention of all who witnessed it. The images, taken by a talented photographer and shared with permission, provide a glimpse into the captivating world of atmospheric phenomena.

Appreciating Nature's Wonders

Experiencing atmospheric optics phenomena such as the sunset Parry and tangent arcs reminds us of the immense beauty and complexity of the natural world. These rare occurrences serve as a reminder to take a moment to appreciate the wonders that surround us, even in the most ordinary of settings. The Dutch skies on that December day treated observers to a visual feast that left them in awe of the magic that can unfold right above our heads.

Observing Atmospheric Optics

For those interested in witnessing atmospheric optics phenomena firsthand, it is essential to keep an eye on weather conditions and be prepared for spontaneous displays. Here are a few tips for observing such phenomena:

• Choose a location with an unobstructed view of the sky, away from light pollution.
• Keep an eye on weather forecasts and look for conditions that favor the formation of ice crystals, such as high cirrus clouds.
• Be patient and allow ample time for the phenomena to develop. Atmospheric optics can be fleeting, and patience is often rewarded with breathtaking displays.
• Consider joining local astronomy or weather enthusiast groups who may share information about upcoming events or provide guidance on observation techniques.

Conclusion

The sunset Parry and tangent arcs witnessed in the Netherlands on December 7th, 2015, were a remarkable display of atmospheric optics. The unique formations created by hexagonal ice crystals drifting within high cirrus clouds left observers in awe of the beauty and complexity of nature. As we gaze upon the sky, let us remember to appreciate the wonders that unfold above us and embrace the opportunity to witness rare and captivating atmospheric phenomena like these.

Netherlands Halos

As sunset approached - and after sunset - on December 7th. '15, Dutch skies had ice halos forming a striking double 'V' of upper Parry and tangent arcs.

The upper arc is the sunvex Parry, the lower the tangent arc.

Both arcs are formed by hexagonal columns drifting in high cirrus with their long axes horizontal. But there the similarity ends.

Tangent arc forming columns have random rotational positions about their long horizontal axis. However, the individual crystals do not necessarily rotate.

Parry arcs are from columns that, for whatever reason, do not have random rotations and keep their uppermost prism side face horizontal. This is a rare orientation and Parry arcs would be even rarer than they are except that very few Parry oriented crystals are needed to produce a bright halo.

Images ©The Photographer and shown with permission

An unusual sighting several minutes after the sun had set at ground level. The high cloud containing the halo forming ice crystals was still sunlit.

Under these conditions the Parry and tangent arcs nearly coincide at the bottom of the 'V' but separate higher up.

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Reference Atmospheric Optics

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