OPOD - Tall sun pillar Barcelona

Last updated on September 16, 2023

OPOD - Tall Sun Pillar Barcelona: A Spectacular Atmospheric Phenomenon

Have you ever witnessed a breathtaking sun pillar stretching towards the sky? Alfons Puertas Castro captured an extraordinary moment when he observed an exceptionally tall and bright sun pillar from the Fabra Observatory in Barcelona, Spain. As the sun rose over the Mediterranean, its rays interacted with density gradients in the atmosphere, causing a fascinating distortion of the sun's shape.

Sun pillars are a mesmerizing atmospheric phenomenon created by the reflection of sunlight off ice crystals found in thin, cold high clouds such as cirrostratus or altostratus. These clouds, which persist throughout the year, provide the perfect conditions for sun pillars to appear across the globe.

Unveiling the Ice Crystals Behind Sun Pillars

The majority of sun pillars arise from hexagonal plate-shaped ice crystals, although they rarely possess the perfect symmetry depicted in some images. These crystals, which often wobble in their orientation, allow sunlight to glint from either their lower or upper faces. The collective glints give rise to the illusion of a vertical shaft of light, creating the distinctive pillar-like appearance. However, it's important to note that there is no actual physical column of light present.

Interestingly, column crystals can also generate sun pillars, albeit less frequently. These crystals have a different shape compared to plate-shaped crystals and tend to produce taller pillars. The exceptionally tall sun pillar observed in Barcelona could potentially be attributed to the presence of column crystals in the atmosphere.

A Play of Light and Shadows

As the sun gradually emerges above the horizon, a magical interplay of light and shadows unfolds. In earlier images captured by Alfons Puertas Castro, only a sliver of the sun is visible, yet the pillar shines brightly against the sky. This phenomenon occurs due to the high altitude at which mirror-like ice crystals reside, already bathed in full sunlight. However, lower-level haze obstructs the lower portions of the pillar, creating a striking contrast between the illuminated upper section and the obscured lower part.

The Dance of Sun Pillars

After sunset, sun pillars continue to captivate observers as they gracefully traverse the horizon, always positioned above the sun. These pillars can persist for an hour or longer, providing ample time to marvel at their beauty and contemplate the wonders of atmospheric optics. It's truly a delightful experience to witness the ethereal movements of these radiant pillars against the backdrop of a darkening sky.

In conclusion, the tall sun pillar observed in Barcelona showcases the captivating beauty of atmospheric optics. Through the interaction of sunlight with ice crystals in the atmosphere, these pillars create an awe-inspiring visual spectacle. Whether formed by hexagonal plate-shaped crystals or rarer column crystals, sun pillars never fail to amaze with their towering presence. So keep your eyes to the sky and be prepared to witness the enchantment of sun pillars wherever you may be.

Tall Sun Pillar - Barcelona

Alfons Puertas Castro saw this exceptionally tall and bright sun pillar from Fabra Observatory at Barcelona, Spain. The sun had not long risen over the Mediterranean. See his earlier images below. Note the flattened sun, distorted by passage of its rays across density gradients in the atmosphere.

Image ©Alfons Puertas Castro, shown with permission

Sun pillars are produced by light reflected by ice crystals in thin and cold high cloud like cirrostratus or altostratus. These clouds are always cold and pillars are visible all year around all over the planet.

What crystals?

Most pillars come from large and wobbling hexagonal plate shaped crystals although they are not usually as perfect as that at right. Sunlight glints from the lower face or internally from the upper one. The collective glints 'appear' as a pillar. There is no 'vertical shaft of light'!

But.. ..Column crystals also generate pillars. Although more rare, they tend to be taller. The Barcelona pillar could be from column crystals.

A little earlier as the sun breaks the horizon.

Only a sliver of sun is visible yet the pillar glows bright. At the high altitude of the mirror like ice crystals the atmosphere is already in full sunlight. Lower level haze blocks out the lower parts of the pillar. It's fun to watch pillars after sunset moving along the horizon always above the sun. Sometimes they last for an hour.

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Reference Atmospheric Optics

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