This photo was taken on a warm September night from a roof terrace in the city of Antwerp, Belgium. It is the last of a series of four almost identical shots. What first looked like a contrail soon turned out to be a reflection of a gas flame from a petrochemical plant in the city's harbour. The "flare pillar" changed in brightness in accordance with the glow of the gas flame. The flame itself is just below the skyline. Note that the pillar is exceptionally long and looks like a string with segments that are not all equally bright. This appearance indicates that the ice cloud that produced the reflection was thick and layered. Such clouds will not only create longer pillars, they will also give them a segmented look because of the different concentrations of ice crystals at different altitudes.

The picture was taken on September 26, 2000 at 10:40 pm. The camera used was a Zenit 12 XP in combination with a 28 mm lens. The film: a Kodak Gold 200 ASA. Exposure time: 8 seconds with aperture set at f/2. The distance between the light source and the camera: 8.6 km (5.3 miles). The altitude of the reflective layer (calculated for the centre of the reflection): approximately 6.1 km (20,013 feet).

[© Wim VAN UTRECHT/CAELESTIA]