Fire and Ice? - Strange Pillars
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Highlights

Emilio Messina ( Landscape Photography ) was taking long exposure photos of an eruption of Mount Etna in Sicily, Italy on June 2, 2019. The exposures revealed vertical light columns seemingly around the volcano.

They look like 'light pillars', seen in very cold weather when street lights are reflected back downwards by low level horizontal plate shaped ice crystals..   But ice in Sicily in June!?

Fortunately we cancalculate the height of any crystals.  The Plough's stars in the background give the columns' angular height at ~16 degrees above the astronomical horizon.   Theground lights could be up to 35 miles distant on the north-west Sicilian coast.  Put that together and the height of the reflecting crystals comes out at roughly 27,000 feet.   It's certainly cold enough up there for ice crystals.

Unusual light pillars from ice far above fiery Etna.










Why columns rather than spots?

A thin cloud layer with exactly horizontal plate crystals would act like a perfect mirror and give a realistic reflection of the the ground lights. This sometimes happens.

A thicker cloud layer acts like a stack of partially reflecting glass plates and that gives columns.   So do slightly wobbly plate crystals.



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