MERINDOL (84) 09.11.2017

On 9 November 2017 at about 22:25, a witness at home noticed an unusual luminous phenomenon in the night sky, describing a “burning cloud” and then a luminous “beam.” The observation continued until 23:00 as the glowing cloud gradually faded. The witness had time to take photographs. No other account was collected. GEIPAN identifies a rare optical phenomenon called a light pillar, also termed a sun pillar. This natural phenomenon occurs when sunlight or moonlight is reflected by ice crystals suspended in the atmosphere and is visible when the Sun or Moon is near the horizon. It can also occur with artificial lights such as streetlights. The witness, in fact, mentioned a reflection of light from a town. In this case the ground-level light source must be some distance away because it was not directly visible. Streetlights can produce pillars through reflections from ice crystals suspended in cold air or in clouds. The Carpentras weather station recorded 1.7° that day. GEIPAN explains this event as the combination of flat ice crystals lower than usual because of cold conditions aloft, and powerful, localized artificial light sources on the ground. The lights could have come from Salon-de-Provence, southwest of the witness in the same direction as the phenomenon. The source refers readers to the article “Colonne Lumineuse” for more information. GEIPAN classifies the case A: observation of an atmospheric light pillar.