OPOD - Extreme Mountain Biking & Halos

Last updated on September 16, 2023

OPOD - Extreme Mountain Biking & Halos: A Mesmerizing Encounter with Atmospheric Optics

Have you ever imagined combining extreme mountain biking with a captivating display of halos in the sky? Well, Ed Stockard and his colleague Robin experienced this incredible phenomenon at Summit Station, situated at the heart of the Greenland Ice Cap. As they braved the bone-chilling temperature of -20°C and winds gusting at 14-18 knots, they were treated to a breathtaking spectacle that merged the thrill of mountain biking with the ethereal beauty of atmospheric optics.

As Ed Stockard's photographs reveal, the sky above them was adorned with a vibrant circumzenithal arc, delicately sculpted by hexagonal plate ice crystals drifting with their large faces almost parallel to the ground. Just below this celestial marvel, a rare 46° halo emerged, caused by poorly oriented or clustered crystals. This deviation from the more common supralateral arc piqued curiosity. The absence of a prominent tangent arc, which typically accompanies column crystals and heralds a supralateral arc, provided a clue to this unusual occurrence.

Moving closer to the sun, another familiar sight graced the sky - the 22° halo. Guarded by sundogs and intersected by the parhelic circle, this halo served as a constant companion throughout their expedition. However, the crystal populations responsible for these optical phenomena underwent a transformation when viewed in their entirety against the backdrop of the sky. Horizontal column crystals created upper and lower tangent arcs, while near the horizon, infralateral arcs painted the heavens with an array of vibrant hues. A subtle hint of a Parry arc added to the visual symphony unfolding above.

Delving further into the intricacies of halo formation, Dave joined the duo to demonstrate how these awe-inspiring displays are crafted from the individual glints of low-level diamond dust crystals. As he shaded the sun, the horizon was embellished with infralateral arcs, adding another layer of mystique to the already enchanting scene.

These captivating moments captured by Ed Stockard's lens offer a glimpse into the mesmerizing world of atmospheric optics. While extreme mountain biking and halos may seem like an unlikely pairing, this unique encounter showcases the harmonious convergence of adventure and natural beauty. Exploring the skies above Summit Station, the Greenland Ice Cap reveals a canvas where ice crystals take center stage, crafting a symphony of light and color.

As we witness the interplay between these celestial phenomena and our earthly pursuits, it serves as a reminder of the boundless wonders that nature has to offer. So, the next time you embark on an adrenaline-fueled adventure, take a moment to gaze skyward. Who knows what breathtaking displays of atmospheric optics await you, merging the thrill of your pursuits with the captivating beauty of the heavens above?

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Extreme Biking ~ Ed Stockard (photostream) is back at Summit Station at the centre of the nearly two mile thick Greenland Ice Cap. Here, colleague Robin shades the sun for a halo display image and gives mountain biking a whole new perspective. The temperature was -20C with 14-18kt winds.

Images ©Ed Stockard, shown with permission

Overhead a colourful circumzenithal arc is sculpted by hexagonal plate ice crystals drifting with their large faces nearly horizontal.

Almost touching it is a rare 46�halo from poorly oriented or cluster crystals. Why a 46° halo rather than the more common supralateral arc? In the top image the 22° halo made by the same crystals is bright and there is little sign of a tangent arc that heralds the column crystals necessary for a supralateral.

Circling closer to the sun is the familiar 22� halo guarded by sundogs and crossed by the parhelic circle.

Crystal populations changed for the all sky view at right. Horizontal column crystals had formed upper and lower tangent arcs and � near the horizon � infralateral arcs of widely separated colours. There is a hint also of a Parry arc.

Dave shades the sun. We see how the halos are formed from the individual glints of low-level diamond dust crystals.

Infralateral arcs colour the horizon.

Note: this article has been automatically converted from the old site and may not appear as intended. You can find the original article here.

Reference Atmospheric Optics

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