Tall Sun Pillar - Barcelona
toptics
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Highlights
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
A little earlier as the sun breaks the horizon.
But.. ..Column crystals also generate pillars. Although more rare, they tend to be taller. The Barcelona pillar could be from column crystals.
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.
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'!
