OPOD - Bucket Ice

Last updated on September 16, 2023

OPOD - Bucket Ice: A Fascinating Encounter with Hexagonal Ice Crystals

Ice, a common substance in our daily lives, exhibits a captivating phenomenon known as hexagonal symmetry. This unique characteristic can be observed in various forms, from the intricate six-sided snowflakes that fall from the sky to the ethereal halos that grace our atmosphere. However, one particular encounter with hexagonal ice crystals stands out – the discovery of a massive crystal in a humble bucket in the backyard of Aidan Forde, located in Killarney, South West Ireland.

The extraordinary growth of this crystal was facilitated by a slow overnight cooling process, allowing a single crystal to form over the surface of the bucket's water. As it grew, the crystal developed dendritic patterns along the directions of the three main 'a' axes of its fundamental hexagonal prism shape. This remarkable phenomenon provides a glimpse into the fascinating world of ice crystal formation.

To comprehend why ice possesses this hexagonal symmetry, we must explore its molecular structure. The arrangement and bonding of four water molecules within a unit cell of the solid give rise to the ice's unique symmetry. The formation of ice crystals involves stacking these basic units, much like building blocks in a wall. The shape and arrangement of these units determine the macro-structure of the ice.

Now that we have delved into the fundamental aspects of ice crystal formation, let us further explore the intriguing world of hexagonal ice and its significance in atmospheric optics:

1. Nature's Artistry: Hexagonal ice crystals showcase nature's artistic prowess, captivating us with their intricate and symmetrical designs. Each crystal is a masterpiece, shaped by the interplay between temperature, humidity, and atmospheric conditions.

2. Snowflake Symmetry: The iconic six-fold symmetry observed in snowflakes arises from the hexagonal structure of ice crystals. As water vapor freezes onto existing ice crystals in clouds, the molecules arrange themselves in a hexagonal lattice, resulting in the formation of symmetrical snowflakes.

3. Halos in the Sky: Hexagonal ice crystals also play a vital role in the formation of atmospheric optical phenomena, such as halos. These captivating rings of light encircle the Sun or Moon, creating a breathtaking spectacle. The hexagonal shape of ice crystals influences the angles at which light is refracted and reflected, giving rise to these mesmerizing halos.

4. Diamond Dust: Another atmospheric phenomenon involving hexagonal ice crystals is known as "diamond dust." These tiny ice crystals, resembling diamond particles, float in the air, creating a shimmering effect when illuminated by sunlight or artificial light sources.

5. Polar Stratospheric Clouds: Hexagonal ice crystals are integral components of polar stratospheric clouds, also known as "nacreous clouds." These iridescent clouds form at high altitudes and are responsible for producing stunning displays of vibrant colors during sunrise and sunset.

6. Ice Crystal Variations: While hexagonal ice crystals dominate our encounters with ice, it is important to note that other types of stable ice structures exist under different conditions. These variations give rise to unique crystal shapes and properties, further adding to the diversity of ice phenomena.

7. Scientific Research: The study of hexagonal ice crystals holds significant importance in scientific research. Understanding their formation and properties helps scientists gain insights into various fields, including meteorology, climatology, and materials science.

8. Artistic Inspiration: Hexagonal ice crystals have long been a source of inspiration for artists and photographers. Their delicate and symmetrical structures provide endless possibilities for creative expression, resulting in stunning visual representations of the natural world.

9. Natural Beauty: Encountering hexagonal ice crystals in various forms reminds us of the awe-inspiring beauty and complexity of our planet. From delicate snowflakes adorning a winter landscape to the enchanting halos that grace our skies, these natural phenomena remind us of the wonders that surround us.

10. Ongoing Exploration: The discovery of Aidan Forde's colossal hexagonal ice crystal in a simple bucket serves as a reminder that there is still much to learn and explore in the realm of atmospheric optics. Each new encounter with these mesmerizing crystals unveils a new chapter in our understanding of the natural world.

In conclusion, hexagonal ice crystals offer a glimpse into the captivating world of atmospheric optics. From their role in the formation of snowflakes and halos to their presence in polar stratospheric clouds and diamond dust, these crystals continue to fascinate and inspire. Aidan Forde's remarkable discovery serves as a testament to the intricate beauty that can be found even in the most unexpected places. As we continue to explore and study these captivating phenomena, we unlock the secrets of our atmosphere and gain a deeper appreciation for the wonders that surround us.

Bucket Ice ~ Aidan Forde discovered this huge hexagonal ice crystal in a bucket in his backyard in Killarney, South West Ireland

©Aidan Forde, shown with permission.

All crystals of the ice we encounter around us (Ice 1h – there are other types stable under different conditions) have hexagonal symmetry. We see it in six sided snowflakes and it is manifest in the halos of the skies.

Here, very slow overnight cooling has enabled a single crystal to grow over the bucket's water surface.

The growth is dendritic along the directions of the three main ‘a’ axes of the fundamental hexagonal prism shape.

Why is ice hexagonal? The symmetry arises from the lowest Gibbs free energy arrangement and bonding of four water molecules within a unit cell of the solid. Ice crystals are built of stacks of these basic units like the bricks in a wall. The shape of the brick and its stacking determine the ice macro-structure.

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Reference Atmospheric Optics

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