Parry & Tangent Arcs - OPOD

Last updated on September 16, 2023

When it comes to atmospheric optics, there are many fascinating phenomena to behold. One such captivating spectacle is the occurrence of Parry and Tangent Arcs. These optical phenomena can be observed in the sky, adding an enchanting touch to our visual experience.

Understanding Parry and Tangent Arcs

Parry Arcs and Tangent Arcs are intricately connected, both visually and structurally. The glow of the upper tangent always extends over the Parry arc, with the latter being a subset of the former. In simpler terms, Parry oriented crystals are a special case of the singly oriented columns that form tangent arcs.

The Ever-Changing Appearance

As the sun's altitude changes throughout the day, the appearance of Parry and Tangent Arcs undergoes dramatic transformations. These arcs are highly dependent on solar altitude, meaning that their shape, size, and intensity can vary significantly depending on the position of the sun in the sky.

An Artist's Perspective

To truly appreciate the beauty of Parry and Tangent Arcs, one must witness them firsthand. Photographer Marc Picco managed to capture the allure of these atmospheric wonders, even amidst the bustling cityscape of Vancouver. His photographs showcase the delicate arcs caught between apartment blocks, allowing us to marvel at nature's artistry amidst an urban backdrop.

The Influence of Crystal Orientation

The formation of Parry and Tangent Arcs is intricately tied to the orientation of ice crystals in the atmosphere. The specific alignment and shape of these crystals play a crucial role in creating the mesmerizing arcs we observe. Understanding the complexities of crystal orientation helps us unravel the mysteries behind these atmospheric phenomena.

Exploring HaloSim Ray Tracing

HaloSim ray tracing offers a valuable tool to study and visualize the context of Parry Arcs. By simulating the path of light through ice crystals, scientists and enthusiasts can gain a deeper understanding of the intricate interplay between sunlight and crystal structures. This simulation provides insights into the formation and behavior of Parry and Tangent Arcs under different solar conditions.

The Role of Solar Altitude

Solar altitude, or the angle at which the sun appears in the sky, has a profound impact on the visibility and characteristics of Parry and Tangent Arcs. At lower sun altitudes, the upper Parry/Tangent group can appear magnificently large, creating a stunning display that captures our imagination. As the sun climbs higher, the arcs may diminish in size or even fade from view, leaving us in awe of their fleeting nature.

The Quest for Originality

While Parry and Tangent Arcs are well-studied atmospheric phenomena, each observation presents an opportunity for unique discoveries. No two occurrences are exactly alike, as variations in crystal alignment, atmospheric conditions, and observer perspective contribute to the individuality of each sighting. This continuous pursuit of originality fuels the fascination and intrigue surrounding these elusive arcs.

A Window into Atmospheric Optics

Parry and Tangent Arcs serve as windows into the fascinating world of atmospheric optics. By observing and studying these ethereal phenomena, we gain valuable insights into the behavior of light in our atmosphere. Exploring the intricacies of ice crystal orientation, solar altitude, and the ever-changing nature of these arcs allows us to deepen our understanding of the optical wonders that grace our skies.

Embracing the Wonder

In a world filled with scientific explanations and rational thinking, Parry and Tangent Arcs remind us of the beauty and wonder that surround us. These enchanting atmospheric optics phenomena serve as a gentle reminder to pause, appreciate, and marvel at the intricate dance between light, crystals, and the ever-changing canvas of our sky. So next time you gaze upwards, take a moment to look for the delicate arcs that grace our atmosphere, and let yourself be captivated by their ethereal allure.

Parry & Tangent Arcs

Caught between apartment bocks in Vancouver by Marc Picco.

All images ©Marc Picco, shown with permission

Close-up of the upper tangent and upper sunvex Parry arcs.

The glow of the upper tangent always extends over the Parry arc. The latter is a sub-set of the upper tangent in the sense that Parry oriented crystals are a special case of the singly oriented columns that make tangent arcs.

HaloSim ray tracing to show the Parry arcs in context. At low sun the upper Parry/upper tangent group can be huge.

These arcs change dramatically in appearance as the solar altitude changes.

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Reference Atmospheric Optics

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