A close up of one of the pillars in the previous picture. Note the unusual fanning out at the top of the pillars, a peculiarity that is also visible in Arto OKSANEN's photo of a light pillar produced by car headlights and included in this sub gallery as OP-PM-02.
On his excellent web site www.atoptics.co.uk, atmospheric optics expert Les COWLEY remarks that ordinary plate crystals are not able to produce these trumpet-like curved tops. "Although horizontal column crystals could contribute" COWLEY writes, "the precise trumpet formation mechanism remains unknown". Photos taken by Aigar TRUHIN with a 30 second interval, first show a weak pencil-shaped pillar and 30 seconds later a weak trumpet shape without the pillar, suggesting two different crystal populations producing each component perhaps in more than one layer (see www.atoptics.co.uk/fz179.htm).
Trumpet or flared pillars have been observed in combination with circumscribed halos around the Moon (see Peter Paul HATTINGA VERSCHURE’s photo in the previous link) and upper and lower tangent arcs (see for example Arto OKSANEN’s photo of a lunar lower tangent arc taken on the same day as his photo of a light pillar caused by car headlights). Both halo types are produced by horizontally oriented column crystals, so it appears correct that column crystals can be responsible for the fanning out of pillars too.
Next is a third photo from this remarkable series.
[© Aigar TRUHIN - photo shown with permission (image found on spaceweather.com)]