There were lengthy and extensive sightings of vertical light pillars in the Philadelphia, Pennsylvania, USA last night from around 7:30 to 8:30 p.m. local time.
See this link for photos and comments: www.nbcphiladelphia.com.
I saw them myself from my home nearly due east, about 25 miles from Philadelphia, which is the 4th largest city in the USA. People living north, west and even south of Philadelphia reported seeing them, as did some other scattered around. You can check the reports yourself.
I found your web site on this phenomenon and posted it on the comments section of the news report above. But I don't think that has garnered much attention and there is still a lot of random speculation. This TV station's weatherman, who didn't see the lights himself, reported that the event was probably "virga" (which I had never heard of), which he described as snowfall refracted by moonlight. I don't think so, given the nature of the phenomenon.
The weather conditions were nearly perfect for the "vertical light pillars in cirriform clouds" explanation. Ground temp was about zero degrees Celsius (32° Fahrenheit) and there were mostly clear skies during the event with snow moving in from the northwest. There was almost no wind, and the area is relatively flat with no mountains. The topography does include some ridges but no mountain peaks. Sunset was at about 5:15 p.m. local time, and I don't believe moonrise was for several more hours, so we can be quite confident that these were not some other kind of light pillars.
There were several VERY bright and stable light pillars and dozens of other fainter light pillars. As in other cases you cite, there are refineries with open-flame burn-off much of the time in the area.
The phrase "vertical light pillars in cirriform clouds" hardly inspires much enthusiasm among people for this unusual phenomenon since it sounds so strange and scientific. May I suggest that you assign a more colloquial name, which I will borrow from one of the other comments I read: "Angels Wings".
I look forward to your response, and I suggest that you contact Glenn "Hurricane" SCHWARTZ at NBC Channel 10 in Philadelphia so he can correct his earlier speculation.
Garnet Valley, Pennsylvania
Our reply :
We are very grateful to Dan Levin for sharing with us his personal sighting of what appears to have been an exceptional spectacle (for more details about the November 19 sightings, see the next entry on this page and the two photos of the lights which we included in our picture galleries).
With regard to the origin of the phenomenon, there can be no doubt: these "vertical light pillars" were unmistakably the mirrored images of ground-based lights reflecting in transparent layers of ice crystals. Immediately after receipt of Mr. LEVIN's mail, we posted this explanation on the NBC Philadelphia Weather Stories forum. Together with several earlier posts with links to our web site, notably by Mr. LEVIN, this seemed to help in putting an end to the random speculation.
In the November 19 display, meteorological conditions were apparently favourable enough for almost every unshielded light to be mirrored in the sky. The quantity and quality of the reflections indicate that the ice-crystal cloud must have been relatively close to the ground (though not close enough to be qualified as "ice mist" because, in that case, the lower part of the pillars would have connected with their light sources). Soundings from a weather balloon released from Pittsburgh on November 20, at 00:00 Zulu Time (i.e. about half an hour before Mr. LEVIN spotted the light pillars) suggest an ice-crystal layer at 2.4 km (1.5 miles). Usually, these cloud layers form at altitudes higher than 3.5 km (2.2 miles), but from time to time they are known to form at lower altitudes as well, especially in northern regions such as Alaska and Finland.
As for assigning a more colloquial name to the pillars, we refer to the final paragraphs of Chapter 2 of our research article on lights pillars in cirriform clouds. At the end of the 19th, beginning of the 20th century, the name "gas comets" was often used to designate the pillars. For several years, we ourselves referred to the lights as "gas flame reflections", but we stopped using that name when we discovered that poorly shielded spotlights can cause them as well. A less technical term would indeed be desirable, but personally we don't think the name "Angel Wings" matches very well the characteristic needle or pencil shape of the reflections.
The pillars seen over Philadelphia are also the subject of one of our case examples.